I have the original image:
I rotate the image with the following Java code:
BufferedImage bi = ImageHelper.rotateImage(bi, -imageSkewAngle);
ImageIO.write(bi, "PNG", new File("out.png"));
as the result I have the following image:
How to remove black bound around the image and make it a proper white rectangle and to not spent much space.. use only the required size for the transformation... equal to original or larger if needed?
The following program contains a method rotateImage that should be equivalent to the rotateImage method that was used in the question: It computes the bounds of the rotated image, creates a new image with the required size, and paints the original image into the center of the new one.
The method additionally receives a Color backgroundColor that determines the background color. In the example, this is set to Color.RED, to illustrate the effect.
The example also contains a method rotateImageInPlace. This method will always create an image that has the same size as the input image, and will also paint the (rotated) original image into the center of this image.
The program creates two panels, the left one showing the result of rotateImage and the right one the result of rotateImageInPlace, together with a slider that allows changing the rotation angle. So the output of this program is shown here:
(Again, Color.RED is just used for illustration. Change it to Color.WHITE for your application)
As discussed in the comments, the goal of not changing the image size may not always be achievable, depending on the contents of the image and the angle of rotation. So for certain angles, the rotated image may not fit into the resulting image. But for the use case of the question, this should be OK: The use case is that the original image already contains a rotated rectangular "region of interest". So the parts that do not appear in the output should usually be the parts of the input image that do not contain relevant information anyhow.
(Otherwise, it would be necessary to either provide more information about the structure of the input image, regarding the border size or the angle of rotation, or one would have to manually figure out the required size by examining the image, pixel by pixel, to see which pixels are black and which ones are white)
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
public class RotateImageWithoutBorder
{
public static void main(String[] args) throws Exception
{
BufferedImage image =
ImageIO.read(new URL("https://i.stack.imgur.com/tMtFh.png"));
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ImagePanel imagePanel0 = new ImagePanel();
imagePanel0.setBackground(Color.BLUE);
ImagePanel imagePanel1 = new ImagePanel();
imagePanel1.setBackground(Color.BLUE);
JSlider slider = new JSlider(0, 100, 1);
slider.addChangeListener(e ->
{
double alpha = slider.getValue() / 100.0;
double angleRad = alpha * Math.PI * 2;
BufferedImage rotatedImage = rotateImage(
image, angleRad, Color.RED);
imagePanel0.setImage(rotatedImage);
BufferedImage rotatedImageInPlace = rotateImageInPlace(
image, angleRad, Color.RED);
imagePanel1.setImage(rotatedImageInPlace);
f.repaint();
});
slider.setValue(0);
f.getContentPane().add(slider, BorderLayout.SOUTH);
JPanel imagePanels = new JPanel(new GridLayout(1,2));
imagePanels.add(imagePanel0);
imagePanels.add(imagePanel1);
f.getContentPane().add(imagePanels, BorderLayout.CENTER);
f.setSize(800,500);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static BufferedImage rotateImage(
BufferedImage image, double angleRad, Color backgroundColor)
{
int w = image.getWidth();
int h = image.getHeight();
AffineTransform at = AffineTransform.getRotateInstance(
angleRad, w * 0.5, h * 0.5);
Rectangle rotatedBounds = at.createTransformedShape(
new Rectangle(0, 0, w, h)).getBounds();
BufferedImage result = new BufferedImage(
rotatedBounds.width, rotatedBounds.height,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g = result.createGraphics();
g.setColor(backgroundColor);
g.fillRect(0, 0, rotatedBounds.width, rotatedBounds.height);
at.preConcatenate(AffineTransform.getTranslateInstance(
-rotatedBounds.x, -rotatedBounds.y));
g.transform(at);
g.setRenderingHint(
RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(image, 0, 0, null);
g.dispose();
return result;
}
private static BufferedImage rotateImageInPlace(
BufferedImage image, double angleRad, Color backgroundColor)
{
int w = image.getWidth();
int h = image.getHeight();
AffineTransform at = AffineTransform.getRotateInstance(
angleRad, w * 0.5, h * 0.5);
Rectangle rotatedBounds = at.createTransformedShape(
new Rectangle(0, 0, w, h)).getBounds();
BufferedImage result = new BufferedImage(
w, h,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g = result.createGraphics();
g.setColor(backgroundColor);
g.fillRect(0, 0, w, h);
at.preConcatenate(AffineTransform.getTranslateInstance(
-rotatedBounds.x - (rotatedBounds.width - w) * 0.5,
-rotatedBounds.y - (rotatedBounds.height - h) * 0.5));
g.transform(at);
g.setRenderingHint(
RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(image, 0, 0, null);
g.dispose();
return result;
}
static class ImagePanel extends JPanel
{
private BufferedImage image;
public void setImage(BufferedImage image)
{
this.image = image;
repaint();
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
if (image != null)
{
g.drawImage(image, 0, 0, null);
}
}
}
}
I'm trying to draw a triangle with a border using the Graphics.drawPolygon() method
The triangle is properly drawn, but how can I calculate the 3 points of the border?
I already did it with a circle, but I can't seem to find a solution for triangle.
A requirement of the instructor as that it cannot use Graphics2D.
My code:
if (xPoints != null && yPoints != null) {
int[] nXPoints = new int[] { xPoints[0] - borderThickness, xPoints[1] - borderThickness,
xPoints[2] - borderThickness };
int[] nYPoints = new int[] { yPoints[0] - borderThickness, yPoints[1] - borderThickness,
yPoints[2] - borderThickness };
g.setColor(borderColor);
g.fillPolygon(nXPoints, nYPoints, 3);
g.setColor(fillColor);
g.fillPolygon(xPoints, yPoints, 3);
}
Edit:
Expected result
Use the Graphics methods drawPolygon() to render the outline and fillPolygon() to fill its interior; both have the required signature, as shown here.
Because "operations that draw the outline of a figure operate by traversing an infinitely thin path between pixels with a pixel-sized pen," cast the graphics context to Graphics2D so that you can use draw() and fill() on the corresponding Shape. This will allow you to specify the outline using setStroke(), illustrated here.
I need it to have a custom thickness…I also don't want to use Graphics2D.
Custom thickness is not supported in the Graphics API. As suggested here, the actual graphics context received by paintComponent() is an instance of Graphics2D, which does support custom stroke geometry.
The things is teacher haven't taught me Graphics2D, so I'm not supposed to use it.
Then simply paint the larger triangle and then the smaller. If this isn't working, then you have an error in you calculation of the larger triangle, and you should edit your question to include a complete example.
I'm looking for a way to do it without Graphics2D…a guy has interpreted the question properly in this comment.
As #Marco13 observes, you need a triangle that is larger than the original one by the borderThickness. You can use AffineTransform to do the scaling. While Graphics can't fill() an arbitrary Shape, such as one created by AffineTransform, it can clip the rendering as required. In the example below, a unit triangle is translated and scaled to the center of an N x N panel; a copy is enlarged by delta. Note how rendering is clipped first to the larger background figure and then to the smaller foreground figure.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* #see https://stackoverflow.com/a/39812618/230513
*/
public class GraphicsBorder {
private static class GraphicsPanel extends JPanel {
private static final int N = 256;
private static final Color FILL = new Color(0x990099);
private static final Color BORDER = new Color(0x66FFB2);
private final Shape fore;
private final Shape back;
public GraphicsPanel(Polygon polygon, int delta) {
AffineTransform a1 = new AffineTransform();
a1.translate(N / 2, N / 2);
a1.scale(N / 3, N / 3);
fore = a1.createTransformedShape(polygon);
AffineTransform a2 = new AffineTransform();
a2.translate(N / 2, N / 2 - delta / 3);
a2.scale(N / 3 + delta, N / 3 + delta);
back = a2.createTransformedShape(polygon);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(BORDER);
g.setClip(back);
g.fillRect(0, 0, N, N);
g.setColor(FILL);
g.setClip(fore);
g.fillRect(0, 0, N, N);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(N, N);
}
}
private void display() {
JFrame f = new JFrame("GraphicsBorder");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Polygon p = new Polygon();
p.addPoint(0, -1);
p.addPoint(1, 1);
p.addPoint(-1, 1);
f.add(new GraphicsPanel(p, 16));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new GraphicsBorder()::display);
}
}
When drawing polygons, Java2D leaves off the right and bottom edges. I understand why this is done. However, I would like to draw something that includes those edges. One thing that occurred to me was to follow fillPolygon with drawPolygon with the same coordinates, but this appears to leave a gap. (See the little triangular image at the bottom.) There are two possibilities, but I can't tell which. To enable antialiasing, I'm doing this:
renderHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
renderHints.put(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHints(renderHints);
One possibility is that the antialiasing is not being done on the alpha channel, so the gap is caused by overdraw. In that case, if the alpha channel were what was being antialiased, the edges would abut properly. The other possibility is that there is just a gap here.
How can I fix this?
Also, I'm not sure, but it appears that the polygon outline may actually be TOO BIG. That is, it may be going further out than the right and bottom edges that I want to include.
Thanks.
-- UPDATE --
Based on a very nice suggestion by Hovercraft Full of Eels, I have made a compilable example:
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
public class polygon {
private static final int WIDTH = 20;
public static void main(String[] args) {
BufferedImage img = new BufferedImage(WIDTH, WIDTH, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
int[] xPoints = {WIDTH / 3, (2*WIDTH) / 3, WIDTH / 3};
int[] yPoints = {0, WIDTH / 2, WIDTH};
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(Color.green);
g2.drawLine(0, WIDTH-1, WIDTH, WIDTH-1);
g2.drawLine(0, 0, WIDTH, 0);
g2.drawLine(WIDTH/3, 0, WIDTH/3, WIDTH);
g2.drawLine((2*WIDTH/3), 0, (2*WIDTH/3), WIDTH);
g2.setColor(Color.black);
g2.drawPolygon(xPoints, yPoints, xPoints.length);
g2.setColor(Color.black);
g2.fillPolygon(xPoints, yPoints, xPoints.length);
g2.dispose();
ImageIcon icon = new ImageIcon(img);
JLabel label = new JLabel(icon);
JOptionPane.showMessageDialog(null, label);
}
}
If you leave the filled polygon red, you get the image below (zoomed by 500%), which shows that the polygon does not extend all the way to the right edge. That is, the vertical green line is corresponds to x=(2*WIDTH)/2, and although the red polygon includes that coordinate, it does not paint any pixels there.
To see the gap problem, I changed red in the program to black. In this image, you can see a subtle gap on the lower right side, where the outline drawn by drawPolygon does not quite meet up with what was drawn with fillPolygon.
Show us your code for your drawing in a simple compilable runnable program. For instance when I try to imitate your image and used RenderingHints, it seemed to produce an appropriate sized image with complete right/bottom edges:
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class Foo002 {
private static final int WIDTH = 20;
public static void main(String[] args) {
BufferedImage img = new BufferedImage(WIDTH, WIDTH,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
int[] xPoints = { WIDTH / 3, (2 * WIDTH) / 3, WIDTH / 3 };
int[] yPoints = { 0, WIDTH / 2, WIDTH };
g2.setColor(Color.black);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setRenderingHint(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
g2.fillPolygon(xPoints, yPoints, xPoints.length);
g2.dispose();
ImageIcon icon = new ImageIcon(img);
JLabel label = new JLabel(icon);
label.setBorder(BorderFactory.createLineBorder(Color.black));
JPanel panel = new JPanel();
panel.add(label);
JOptionPane.showMessageDialog(null, panel);
}
}
If you can show us a similar program that reproduces your problem, then we can give you better help.
I like the convenience of ImageIcon, shown by #HFOE, but this variation may make it a little easier to see what's happening. From the Graphics API,
Operations that draw the outline of a figure operate by traversing an
infinitely thin path between pixels with a pixel-sized pen that hangs
down and to the right of the anchor point on the path. Operations that
fill a figure operate by filling the interior of that infinitely thin
path.
In contrast, Graphics2D must follow more complex rules for antialiasing, which allow it to "draw outside the lines."
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
/** #see http://stackoverflow.com/questions/7701097 */
public class PixelView extends JPanel {
private static final int SIZE = 20;
private static final int SCALE = 16;
private BufferedImage img;
public PixelView(Color fill) {
this.setBackground(Color.white);
this.setPreferredSize(new Dimension(SCALE * SIZE, SCALE * SIZE));
img = new BufferedImage(SIZE, SIZE, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
int[] xPoints = {SIZE / 3, (2 * SIZE) / 3, SIZE / 3};
int[] yPoints = {0, SIZE / 2, SIZE};
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(Color.green);
g2.drawLine(0, SIZE - 1, SIZE, SIZE - 1);
g2.drawLine(0, 0, SIZE, 0);
g2.drawLine(SIZE / 3, 0, SIZE / 3, SIZE);
g2.drawLine((2 * SIZE / 3), 0, (2 * SIZE / 3), SIZE);
g2.setColor(Color.black);
g2.drawPolygon(xPoints, yPoints, xPoints.length);
g2.setColor(fill);
g2.fillPolygon(xPoints, yPoints, xPoints.length);
g2.dispose();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, getWidth(), getHeight(), null);
}
private static void display() {
JFrame f = new JFrame("PixelView");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLayout(new GridLayout(1, 0));
f.add(new PixelView(Color.black));
f.add(new PixelView(Color.red));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
display();
}
});
}
}
Sometimes "the graphics pen hangs down and to the right from the path it traverses", and sometimes it doesn't.
I don't have any clear idea how to predict when it will or won't, but I have observed that RenderingHints.VALUE_STROKE_PURE can sometimes be used to alter the behavior, by trial and error.
In particular, I found that if you turn on STROKE_PURE during your drawPolygon() calls in your program,
it will make them match up with your fillPolygon() calls, as you desire.
I did a little study showing the effect of the STROKE_CONTROL hint, which is one of:
STROKE_NORMALIZE (the default, on my system)
STROKE_PURE
on the following calls:
drawLine()
drawPolygon()
fillPolygon()
in both antialiasing modes:
ANTIALIASING_OFF
ANTIALIASING_ON
And there is one more annoying dimension that apparently matters as well:
rendered directly to a JComponent on the screen
rendered to a BufferedImage.
Here are the results when rendering directly to a visible JComponent:
And here are the results when rendering into a BufferedImage:
(Notice the two cases in which the two pictures differ, i.e. in which direct rendering differs from BufferedImage rendering:
ANTIALIAS_OFF/STROKE_NORMALIZE/fillPolygon and ANTIALIAS_OFF/STROKE_PURE/drawPolygon.)
Overall, there doesn't seem to be much rhyme or reason to the whole thing.
But we can make the following specific observations based on the above pictures:
Observation #1:
If you want your antialiased drawPolygon()s and antialiased fillPolygon()s to match up well
(the original question), then turn on STROKE_PURE during the antialiased drawPolygon() calls.
(It doesn't matter whether it's on during the antialiased fillPolygon() calls.)
Observation #2:
If you want your antialiased fillPolygon()s and non-antialiased fillPolygon()s
to match up (because, say, your app allows the user to switch antialiasing on and off,
and you don't want the picture to jump northwest and southeast each time they do that),
then turn on STROKE_PURE during the non-antialiased fillPolygon() calls.
Here is the program I used to generate the pictures above.
My results are from compiling and running it it with opensdk11 on linux;
I'd be interested to know if anyone gets any different results on different platforms.
/** Study the effect of STROKE_PURE. */
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;
#SuppressWarnings("serial")
public final class AntiAliasingStudy {
// These can be fiddled with.
final static int patchWidth = 24; // keep this a multiple of 4 for sanity
final static int patchHeight = 20; // keep this a multiple of 4 for sanity
final static int borderThickness = 4;
final static int mag = 6;
// derived quantities
final static int totalWidth = 5*borderThickness + 4*patchWidth;
final static int totalHeight = 4*borderThickness + 3*patchHeight;
private static void drawLittleStudy(Graphics2D g2d,
int x00, int y00,
int patchWidth, int patchHeight, int borderThickness, int totalWidth, int totalHeight) {
g2d.setColor(new java.awt.Color(240,240,240));
g2d.fillRect(x00,y00,totalWidth, totalHeight);
for (int row = 0; row < 3; ++row) {
for (int col = 0; col < 4; ++col) {
int x0 = x00 + borderThickness + col*(patchWidth+borderThickness);
int y0 = y00 + borderThickness + row*(patchHeight+borderThickness);
int x1 = x0 + patchWidth;
int y1 = y0 + patchHeight;
g2d.setColor(java.awt.Color.WHITE);
g2d.fillRect(x0, y0, patchWidth, patchHeight);
boolean antialias = (col >= 2);
boolean pure = (col % 2 == 1);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, antialias ? RenderingHints.VALUE_ANTIALIAS_ON : RenderingHints.VALUE_ANTIALIAS_OFF);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, pure ? RenderingHints.VALUE_STROKE_PURE : RenderingHints.VALUE_STROKE_NORMALIZE);
g2d.setColor(java.awt.Color.RED);
if (row == 0) {
// lines (drawLine)
// diagonals
g2d.drawLine(x0,y1, x1,y0);
g2d.drawLine(x0,y0, x1,y1);
// orthogonals
g2d.drawLine((x0+patchWidth/4),y0, (x0+patchWidth*3/4),y0);
g2d.drawLine((x0+patchWidth/4),y1, (x0+patchWidth*3/4),y1);
g2d.drawLine(x0,(y0+patchHeight/4), x0,(y0+patchHeight*3/4));
g2d.drawLine(x1,(y0+patchHeight/4), x1,(y0+patchHeight*3/4));
} else if (row == 1) {
// outlines (drawPolygon)
// A stopsign
g2d.drawPolygon(new int[] {x0+patchWidth/2-2, x0, x0, x0+patchWidth/2-2, x0+patchWidth/2+2, x1, x1, x0+patchWidth/2+2},
new int[] {y0, y0+patchHeight/2-2, y0+patchHeight/2+2, y1, y1, y0+patchHeight/2+2, y0+patchHeight/2-2, y0},
8);
} else if (row == 2) {
// fill (fillPolygon)
// A stopsign
g2d.fillPolygon(new int[] {x0+patchWidth/2-2, x0, x0, x0+patchWidth/2-2, x0+patchWidth/2+2, x1, x1, x0+patchWidth/2+2},
new int[] {y0, y0+patchHeight/2-2, y0+patchHeight/2+2, y1, y1, y0+patchHeight/2+2, y0+patchHeight/2-2, y0},
8);
}
}
}
} // drawLittleStudy
// Show a study, previously created by drawLittleStudy(), magnified and annotated.
private static void showMagnifiedAndAnnotatedStudy(Graphics g,
BufferedImage studyImage,
int x00, int y00,
int patchWidth, int patchHeight, int borderThickness, int totalWidth, int totalHeight, int mag,
ImageObserver imageObserver) {
// Magnify the image
g.drawImage(studyImage,
/*dst*/ x00,y00,x00+totalWidth*mag,y00+totalHeight*mag,
/*src*/ 0,0,totalWidth,totalHeight,
imageObserver);
// Draw annotations on each picture in black,
// in the highest quality non-biased mode
// (now that we know what that is!)
g.setColor(java.awt.Color.BLACK);
((Graphics2D)g).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
((Graphics2D)g).setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
for (int row = 0; row < 3; ++row) {
for (int col = 0; col < 4; ++col) {
int x0 = borderThickness + col*(patchWidth+borderThickness);
int y0 = borderThickness + row*(patchHeight+borderThickness);
int x1 = x0 + patchWidth;
int y1 = y0 + patchHeight;
if (false) {
g.drawLine(x00+x0*mag,y00+y0*mag, x00+x1*mag,y00+y0*mag);
g.drawLine(x00+x1*mag,y00+y0*mag, x00+x1*mag,y00+y1*mag);
g.drawLine(x00+x1*mag,y00+y1*mag, x00+x0*mag,y00+y1*mag);
g.drawLine(x00+x0*mag,y00+y1*mag, x00+x0*mag,y00+y0*mag);
}
if (row == 0) {
// diagonals
g.drawLine(x00+x0*mag,y00+y1*mag, x00+x1*mag,y00+y0*mag);
g.drawLine(x00+x0*mag,y00+y0*mag, x00+x1*mag,y00+y1*mag);
// orthogonals
g.drawLine(x00+(x0+patchWidth/4)*mag,y00+y0*mag, x00+(x0+patchWidth*3/4)*mag,y00+y0*mag);
g.drawLine(x00+(x0+patchWidth/4)*mag,y00+y1*mag, x00+(x0+patchWidth*3/4)*mag,y00+y1*mag);
g.drawLine(x00+x0*mag,y00+(y0+patchHeight/4)*mag, x00+x0*mag,y00+(y0+patchHeight*3/4)*mag);
g.drawLine(x00+x1*mag,y00+(y0+patchHeight/4)*mag, x00+x1*mag,y00+(y0+patchHeight*3/4)*mag);
} else { // row 1 or 2
// A stopsign
g.drawPolygon(new int[] {x00+(x0+patchWidth/2-2)*mag, x00+x0*mag, x00+x0*mag, x00+(x0+patchWidth/2-2)*mag, x00+(x0+patchWidth/2+2)*mag, x00+x1*mag, x00+x1*mag, x00+(x0+patchWidth/2+2)*mag},
new int[] {y00+y0*mag, y00+(y0+patchHeight/2-2)*mag, y00+(y0+patchHeight/2+2)*mag, y00+y1*mag, y00+y1*mag, y00+(y0+patchHeight/2+2)*mag, y00+(y0+patchHeight/2-2)*mag, y00+y0*mag},
8);
}
}
}
FontMetrics fm = g.getFontMetrics();
{
String[][] texts = {
{"ANTIALIAS_OFF", "STROKE_NORMALIZE"},
{"ANTIALIAS_OFF", "STROKE_PURE"},
{"ANTIALIAS_ON", "STROKE_NORMALIZE"},
{"ANTIALIAS_ON", "STROKE_PURE"},
};
for (int col = 0; col < 4; ++col) {
int xCenter = borderThickness*mag + col*(patchWidth+borderThickness)*mag + patchWidth*mag/2;
{
int x = x00 + xCenter - fm.stringWidth(texts[col][0])/2;
int y = y00 + 3*(patchHeight+borderThickness)*mag + fm.getAscent();
g.drawString(texts[col][0], x,y);
x = xCenter - fm.stringWidth(texts[col][1])/2;
y += fm.getHeight();
g.drawString(texts[col][1], x,y);
}
}
}
{
String[] texts = {
"drawLine",
"drawPolygon",
"fillPolygon",
};
for (int row = 0; row < 3; ++row) {
int yCenter = y00 + borderThickness*mag + row*(patchHeight+borderThickness)*mag + patchHeight*mag/2;
int x = x00 + 4*(patchWidth+borderThickness)*mag + 10;
g.drawString(texts[row], x,yCenter);
}
}
} // showMagnifiedAndAnnotatedStudy
private static Dimension figureOutPreferredSize(FontMetrics fm) {
int preferredWidth = (totalWidth-borderThickness)*mag + 10 + fm.stringWidth("drawPolygon") + 9;
int preferredHeight = fm.getHeight() + totalHeight + (totalHeight-borderThickness)*mag + 2*fm.getHeight() + 2;
return new Dimension(preferredWidth, preferredHeight);
}
private static class IndirectExaminationView extends JComponent {
public IndirectExaminationView() {
setFont(new Font("Times", Font.PLAIN, 12));
setPreferredSize(figureOutPreferredSize(getFontMetrics(getFont())));
}
#Override public void paintComponent(Graphics g) {
FontMetrics fm = g.getFontMetrics();
g.setColor(java.awt.Color.BLACK);
g.drawString("through BufferedImage:", 0,fm.getAscent());
// The following seem equivalent
java.awt.image.BufferedImage studyImage = new java.awt.image.BufferedImage(totalWidth, totalHeight, java.awt.image.BufferedImage.TYPE_INT_ARGB);
//java.awt.image.BufferedImage studyImage = (BufferedImage)this.createImage(totalWidth, totalHeight);
drawLittleStudy(studyImage.createGraphics(),
0,0,
patchWidth, patchHeight, borderThickness, totalWidth, totalHeight);
Graphics2D studyImageGraphics2D = studyImage.createGraphics();
g.drawImage(studyImage,
/*dst*/ 0,fm.getHeight(),totalWidth,fm.getHeight()+totalHeight,
/*src*/ 0,0,totalWidth,totalHeight,
this);
showMagnifiedAndAnnotatedStudy(g, studyImage,
0,fm.getHeight()+totalHeight,
patchWidth, patchHeight, borderThickness, totalWidth, totalHeight, mag, this);
}
} // DirectExaminationView
private static class DirectExaminationView extends JComponent {
public DirectExaminationView() {
setFont(new Font("Times", Font.PLAIN, 12));
setPreferredSize(figureOutPreferredSize(getFontMetrics(getFont())));
}
private BufferedImage imgFromTheRobot = null;
#Override public void paintComponent(Graphics g) {
final FontMetrics fm = g.getFontMetrics();
g.setColor(java.awt.Color.BLACK);
g.drawString("direct to JComponent:", 0,fm.getAscent());
drawLittleStudy((Graphics2D)g,
0,fm.getHeight(),
patchWidth, patchHeight, borderThickness, totalWidth, totalHeight);
if (imgFromTheRobot != null) {
System.out.println(" drawing image from robot");
showMagnifiedAndAnnotatedStudy(g, imgFromTheRobot,
0, fm.getHeight()+totalHeight,
patchWidth, patchHeight, borderThickness, totalWidth, totalHeight, mag, this);
imgFromTheRobot = null;
} else {
System.out.println(" scheduling a robot");
g.drawString("*** SCREEN CAPTURE PENDING ***", 0, fm.getHeight()+totalHeight+fm.getHeight()+fm.getHeight());
// Most reliable way to do it seems to be to put it on a timer after a delay.
Timer timer = new Timer(1000/2, new ActionListener() {
#Override public void actionPerformed(ActionEvent ae) {
System.out.println(" in timer callback");
Robot robot;
try {
robot = new Robot();
} catch (AWTException e) {
System.err.println("caught AWTException: "+e);
throw new Error(e);
}
Point myTopLeftOnScreen = getLocationOnScreen();
Rectangle rect = new Rectangle(
myTopLeftOnScreen.x, myTopLeftOnScreen.y + fm.getHeight(),
totalWidth,totalHeight);
BufferedImage img = robot.createScreenCapture(rect);
imgFromTheRobot = img;
repaint();
System.out.println(" out timer callback");
}
});
timer.setRepeats(false);
timer.start();
}
}
} // DirectExaminationView
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
#Override public void run()
{
final JFrame directFrame = new JFrame("direct to JComponent") {{
getContentPane().add(new DirectExaminationView());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocation(0,0);
setVisible(true);
}};
new JFrame("through BufferedImage") {{
getContentPane().add(new IndirectExaminationView());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocation(directFrame.getWidth(),0);
setVisible(true);
}};
}
});
}
} // class AntiAliasingStudy
I am trying to draw horizontal and vertical lines on a bufferedimage. It should end up looking like a grid of cells. But when I run the code, I see only two lines: the leftmost line and the topmost line (ie. a line from 0,0 to 0,height of image & 0,0 to width of image,0) Heres the code snippet:
BufferedImage mazeImage = new BufferedImage(imgDim.width, imgDim.height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = mazeImage.createGraphics();
g2d.setBackground(Color.WHITE);
g2d.fillRect(0, 0, imgDim.width, imgDim.height);
g2d.setColor(Color.BLACK);
BasicStroke bs = new BasicStroke(2);
g2d.setStroke(bs);
// draw the black vertical and horizontal lines
for(int i=0;i<21;i++){
g2d.drawLine((imgDim.width+2)*i, 0, (imgDim.width+2)*i, imgDim.height-1);
g2d.drawLine(0, (imgDim.height+2)*i, imgDim.width-1, (imgDim.height+2)*i);
}
And the overriden paint method:
public void paint(Graphics g) {
g.drawImage(mazeImage, 0, 0, this);
}
This is all in a class called RobotMaze that extends JPanel. Any help is appreciated.
import java.awt.*;
import java.awt.image.*;
import javax.swing.*;
class GridLines {
public static void main(String[] args) {
Dimension imgDim = new Dimension(200,200);
BufferedImage mazeImage = new BufferedImage(imgDim.width, imgDim.height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = mazeImage.createGraphics();
g2d.setBackground(Color.WHITE);
g2d.fillRect(0, 0, imgDim.width, imgDim.height);
g2d.setColor(Color.BLACK);
BasicStroke bs = new BasicStroke(2);
g2d.setStroke(bs);
// draw the black vertical and horizontal lines
for(int i=0;i<21;i++){
// unless divided by some factor, these lines were being
// drawn outside the bound of the image..
g2d.drawLine((imgDim.width+2)/20*i, 0, (imgDim.width+2)/20*i,imgDim.height-1);
g2d.drawLine(0, (imgDim.height+2)/20*i, imgDim.width-1, (imgDim.height+2)/20*i);
}
ImageIcon ii = new ImageIcon(mazeImage);
JOptionPane.showMessageDialog(null, ii);
}
}
Print out your coordinates and you will see that you are plotting points outside the width and height of the image:
System.out.printf("Vertical: (%d,%d)->(%d,%d)\n",(imgDim.width+2)*i, 0, (imgDim.width+2)*i, imgDim.height-1);
System.out.printf("Horizontal: (%d,%d)->(%d,%d)\n",0, (imgDim.height+2)*i, imgDim.width-1, (imgDim.height+2)*i);
How do you expect the result of (imgDim.width+2)*i to be within the image boundaries if i > 0?