I'm currently experimenting with my first custom View in android and have been trying to draw points on a canvas via a onTouchEvent but have failed after several attempts. The View does detect my touches and successfully prints out a System.out.println message when touched however it still doesn't draw on the canvas.
After several various attempts this is what I came up with:
package com.techdigy.testapp;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class DrawingBoard extends View {
Canvas canvas;
Bitmap bmp;
BitmapDrawable temp;
public DrawingBoard(Context context, AttributeSet attributeSet) {
super(context,attributeSet);
// TODO Auto-generated constructor stub
}
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
canvas = new Canvas();
}
protected void onDraw(Canvas canvas) {
//draw view
}
public boolean onTouchEvent(MotionEvent event) {
//detect user touch
float touchX = event.getX();
float touchY = event.getY();
Paint paint = new Paint();
System.out.println("test");
this.canvas.drawPoint(touchX, touchY, paint);
temp = new BitmapDrawable(this.bmp);
this.setBackground(this.temp);
invalidate();
return true;
}
}
try this...
public class DrawingBoard extends View {
private Bitmap bmp;
private float touchX;
private float touchY;
private Paint paint;
public DrawingBoard(Context context, AttributeSet attributeSet) {
super(context, attributeSet);
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
}
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
setBackgroundDrawable(new BitmapDrawable(getResources(), bmp));
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawPoint(touchX, touchY, paint);
}
public boolean onTouchEvent(MotionEvent event) {
// detect user touch
touchX = event.getX();
touchY = event.getY();
System.out.println("test");
invalidate();
return true;
}
}
Related
I build this class to draw on screen to implement some brushes created via differents Paints and paths.
Currently is drawing a square based on user touch movement, but the draw path is being rotated by the draw direction of the touch. I tried to apply a rect without no luck and I don't found any related info about this phenom
EDIT :
This image is from current result
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
public class RachetBasic extends androidx.appcompat.widget.AppCompatImageView {
private Canvas canvas;
private Bitmap bitmap;
private Paint bitmapPaint = new Paint(Paint.DITHER_FLAG);
private Path squarePath = new Path();
private Paint squarePaint = new Paint();
public RachetBasic(Context context) {
super(context);
}
public RachetBasic(Context context, AttributeSet attrs) {
super(context, attrs);
}
public RachetBasic(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onSizeChanged(int width, int height, int oldw, int oldh) {
super.onSizeChanged(width, height, oldw, oldh);
squarePaint.setAntiAlias(true);
squarePaint.setDither(true);
squarePaint.setStyle(Paint.Style.STROKE);
squarePaint.setStrokeCap(Paint.Cap.SQUARE);
squarePaint.setStrokeWidth(80);
squarePaint.setColor(Color.BLUE);
bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(bitmap, 0, 0, bitmapPaint);
canvas.drawPath(squarePath, squarePaint);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
if (event.getAction() == MotionEvent.ACTION_DOWN) {
squarePath.moveTo(x, y);
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
squarePath.lineTo(x, y);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
squarePath.lineTo(x, y);
canvas.drawPath(squarePath, squarePaint);
squarePath.reset();
}
invalidate();
return true;
}
}
public class MainActivity extends androidx.appcompat.app.AppCompatActivity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new RachetBasic(MainActivity.this));
}
}
I need help with this thing
I draw line on canvas and i need to be able to modify the position after it's been drawn. I search and try a lot of things, but no one seems that it works
I want to select one of the ends of the line and dragging them in another position
Can someone give me and advice?
Please try this.In this you can draw and edit the line.
class Drawing extends View{
private Canvas mCanvas = null;
private Path mPath = null;
private Paint mBitmapPaint = null;
private Bitmap mBitmap = null;
private Bitmap bit=null;
private Paint mPaint = null;
private MainActivity baseMainActivity = null;
public interface onDrawingViewSingleTap{
void onDrawingViewTap(float x , float y);
}
public Drawing(Context c) {
super(c);
baseMainActivity=(MainActivity) c;
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.YELLOW);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(6);//This sets the width of signature
Display display =baseMainActivity.getWindowManager().getDefaultDisplay();
mBitmap = Bitmap.createBitmap(display.getWidth(), display.getHeight(), Bitmap.Config.ARGB_8888);// 320*480 // For setting size of screen to draw Bitmap
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mCanvas = new Canvas(mBitmap);
onDraw(mCanvas);
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}
#Override
protected void onDraw(Canvas canvas) {
try{
canvas.drawColor(Color.TRANSPARENT);//Color.WHITE //To change background color of Application
if(bit!=null)
canvas.drawBitmap(bit, 0, 0, mBitmapPaint);
else
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
}catch(Exception e){}
if(bit==null)
canvas.drawPath(mPath, mPaint);
bit=null;
}
private float mX, mY;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x+1;
mY = y+1;
}
private void touch_upline(float x,float y) {
mPath.lineTo(mX, mY);
mCanvas.drawLine(mX, mY, x, y, mPaint);
mPath.reset();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
eraseAll();
touch_upline(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_upline(x,y);
invalidate();
break;
}
return true;
}
public void eraseAll()
{
mBitmap.eraseColor(android.graphics.Color.TRANSPARENT);
mCanvas = new Canvas(mBitmap);
}
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
RelativeLayout relativeLayout= (RelativeLayout) (findViewById(R.id.mainLayout));
relativeLayout.addView(new Drawing(this));
}
}
I want to draw circle by canvas. Here is my code:
[MyActivity.java]:
public class MyActivity extends Activity
{
public void onCreate(Bundle savedInstanceState)
{
...
setContentView(new View(this,w,h));
}
}
[View.java]:
public class View extends SurfaceView
{
public View(Context context, int w, int h)
{
super(context);
Canvas grid = new Canvas(Bitmap.createBitmap(h,w, Bitmap.Config.ARGB_8888));
grid. drawColor(Color.WHITE);
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
grid.drawCircle(w/2, h/2 , w/2, paint);
}
}
So I have just black screen without circle.
Why it does not work? How to fix it?
You can override the onDraw method of your view and draw the circle.
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawCircle(x, y, radius, paint);
}
For a better reference on drawing custom views check out the official Android documentation.
http://developer.android.com/training/custom-views/custom-drawing.html
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(new MyView(this));
}
public class MyView extends View
{
Paint paint = null;
public MyView(Context context)
{
super(context);
paint = new Paint();
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
int x = getWidth();
int y = getHeight();
int radius;
radius = 100;
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
canvas.drawPaint(paint);
// Use Color.parseColor to define HTML colors
paint.setColor(Color.parseColor("#CD5C5C"));
canvas.drawCircle(x / 2, y / 2, radius, paint);
}
}
}
Edit
if you want to draw circle at centre. You could also translate your entire canvas to center then draw circle at center.using
canvas.translate(getWidth()/2f,getHeight()/2f);
canvas.drawCircle(0,0, radius, paint);
These two link also help
http://www.compiletimeerror.com/2013/09/introduction-to-2d-drawing-in-android.html#.VIg_A5SSy9o
http://android-coding.blogspot.com/2012/04/draw-circle-on-canvas-canvasdrawcirclet.html
public class CircleView extends View {
private static final String COLOR_HEX = "#E74300";
private final Paint drawPaint;
private float size;
public CircleView(final Context context, final AttributeSet attrs) {
super(context, attrs);
drawPaint = new Paint();
drawPaint.setColor(Color.parseColor(COLOR_HEX));
drawPaint.setAntiAlias(true);
setOnMeasureCallback();
}
#Override
protected void onDraw(final Canvas canvas) {
super.onDraw(canvas);
canvas.drawCircle(size, size, size, drawPaint);
}
private void setOnMeasureCallback() {
ViewTreeObserver vto = getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
removeOnGlobalLayoutListener(this);
size = getMeasuredWidth() / 2;
}
});
}
#TargetApi(Build.VERSION_CODES.JELLY_BEAN)
private void removeOnGlobalLayoutListener(ViewTreeObserver.OnGlobalLayoutListener listener) {
if (Build.VERSION.SDK_INT < 16) {
getViewTreeObserver().removeGlobalOnLayoutListener(listener);
} else {
getViewTreeObserver().removeOnGlobalLayoutListener(listener);
}
}
}
Xml example: will produce a circle of 5dp
<com.example.CircleView
android:layout_width="10dp"
android:layout_height="10dp"/>
If you are using your own CustomView extending View class, you need to call canvas.invalidate() method which will internally call onDraw method. You can use default API for canvas to draw a circle. The x, y cordinate define the center of the circle. You can also define color and styling in paint & pass the paint object.
public class CustomView extends View {
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
setupPaint();
}
}
Define default paint settings and canvas (Initialise paint in constructor so that you can reuse the same object everywhere and change only specific settings wherever required)
private Paint drawPaint;
// Setup paint with color and stroke styles
private void setupPaint() {
drawPaint = new Paint();
drawPaint.setColor(Color.BLUE);
drawPaint.setAntiAlias(true);
drawPaint.setStrokeWidth(5);
drawPaint.setStyle(Paint.Style.FILL_AND_STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
}
And initialise canvas object
private Canvas canvas;
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
this.canvas = canvas;
canvas.drawCircle(xCordinate, yCordinate, RADIUS, drawPaint);
}
And finally, for every view refresh or new draw on the screen, you need to call invalidate method. Remember your entire view is redrawn, hence this is an expensive call. Make sure you do only the necessary operations in onDraw
canvas.invalidate();
For more details on canvas drawing refer https://medium.com/#mayuri.k18/android-canvas-for-drawing-and-custom-views-e1a3e90d468b
#Override
public void onDraw(Canvas canvas){
canvas.drawCircle(xPos, yPos,radius, paint);
}
Above is the code to render a circle. Tweak the parameters to your suiting.
Try this
The entire code for drawing a circle or download project source code and test it on your android studio. Draw circle on canvas programmatically.
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.widget.ImageView;
public class Shape {
private Bitmap bmp;
private ImageView img;
public Shape(Bitmap bmp, ImageView img) {
this.bmp=bmp;
this.img=img;
onDraw();
}
private void onDraw(){
Canvas canvas=new Canvas();
if (bmp.getWidth() == 0 || bmp.getHeight() == 0) {
return;
}
int w = bmp.getWidth(), h = bmp.getHeight();
Bitmap roundBitmap = getRoundedCroppedBitmap(bmp, w);
img.setImageBitmap(roundBitmap);
}
public static Bitmap getRoundedCroppedBitmap(Bitmap bitmap, int radius) {
Bitmap finalBitmap;
if (bitmap.getWidth() != radius || bitmap.getHeight() != radius)
finalBitmap = Bitmap.createScaledBitmap(bitmap, radius, radius,
false);
else
finalBitmap = bitmap;
Bitmap output = Bitmap.createBitmap(finalBitmap.getWidth(),
finalBitmap.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, finalBitmap.getWidth(),
finalBitmap.getHeight());
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(Color.parseColor("#BAB399"));
canvas.drawCircle(finalBitmap.getWidth() / 2 + 0.7f, finalBitmap.getHeight() / 2 + 0.7f, finalBitmap.getWidth() / 2 + 0.1f, paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(finalBitmap, rect, rect, paint);
return output;
}
Here is example to draw stroke circle canvas
val paint = Paint().apply {
color = Color.RED
style = Paint.Style.STROKE
strokeWidth = 10f
}
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
canvas?.drawCircle(200f, 100f, 100f, paint)
}
Result
Example to draw solid circle canvas
val paint = Paint().apply {
color = Color.RED
}
override fun onDraw(canvas: Canvas?) {
super.onDraw(canvas)
canvas?.drawCircle(200f, 100f, 100f, paint)
}
Result
Hope it help
private Paint green = new Paint();
private int greenx , greeny;
green.setColor(Color.GREEN);
green.setAntiAlias(false);
canvas.drawCircle(greenx,greeny,20,green);
I have implemented zoom on my custom made view which draws a grid onto a canvas, but the zooming won't work if I put both fingers on the screen simultaneously. I have to first put one, then the other.
I followed this blog post by Adam Powell to implement zoom, and made this custom view:
public class ZoomView extends View{
private float width;
private float height;
Paint lineColor;
Paint bgColor;
private float mScaleFactor;
private ScaleGestureDetector scaleDetector;
public CanvasView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
lineColor = new Paint();
lineColor.setColor(getResources().getColor(R.color.white));
bgColor = new Paint();
bgColor.setColor(getResources().getColor(R.color.black));
mScaleFactor = 1;
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh){
width = w/9;
height = h/9;
super.onSizeChanged(w,h,oldw,oldh);
}
#Override
protected void onDraw(Canvas canvas){
super.onDraw(canvas);
canvas.save();
canvas.scale(mScaleFactor, mScaleFactor); //for zooming
for(int i=0; i <= 9; i++){
canvas.drawLine(0,i*height, 9*width,i*height,lineColor);
canvas.drawLine(i*width, 0, i*width, 9*height, lineColor);
}
canvas.restore();
}
#Override
public boolean onTouchEvent(MotionEvent ev){
mScaleDetector.onTouchEvent(ev);
return true;
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
setMeasuredDimension(800, 1000);
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
invalidate();
return true;
}
}
}
So why is the zooming behaving this way?
Any help would be greatly appreciated. Thanks!
This may look like a silly question, but does the multi touch behavior work on other apps (Maps for example) at this device?
I've tested your code (with minor changes, see below) on an LG Optimus Black, Android 4.0.3, and it worked, both fingers simultaneously.
package com.example.teste;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class ZoomView extends View {
private float width;
private float height;
Paint lineColor;
Paint bgColor;
private float mScaleFactor;
private ScaleGestureDetector mScaleDetector;
public ZoomView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
lineColor = new Paint();
lineColor.setColor(getResources().getColor(R.color.ics_blue_bright));
bgColor = new Paint();
bgColor.setColor(getResources().getColor(R.color.black));
mScaleFactor = 1;
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
width = w / 9;
height = h / 9;
super.onSizeChanged(w, h, oldw, oldh);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.scale(mScaleFactor, mScaleFactor); // for zooming
for (int i = 0; i <= 9; i++) {
canvas.drawLine(0, i * height, 9 * width, i * height, lineColor);
canvas.drawLine(i * width, 0, i * width, 9 * height, lineColor);
}
canvas.restore();
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
mScaleDetector.onTouchEvent(ev);
return true;
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(800, 1000);
}
private class ScaleListener extends
ScaleGestureDetector.SimpleOnScaleGestureListener {
#Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
invalidate();
return true;
}
}
}
i have try to draw a finger paint in android using Canvas. I have used the paint for Coloring the Current path.Remove and Appear the paths using undo redo option.But undo Redo works well. i use the Red color for Paint if i use the another color for drawing all the previous paths are changed to current color.
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
public class CustomView extends View implements OnTouchListener {
public Canvas mCanvas;
private Path mPath;
public Paint mPaint, mBitmapPaint;
Bitmap mBitmap;
Canvas canvas;
TabletActivity tabletActivity;
public ArrayList<Path> paths = new ArrayList<Path>();
public ArrayList<Path> undonePaths = new ArrayList<Path>();
private Bitmap im;
public CustomView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(6);
mCanvas = new Canvas();
mPath = new Path();
im = BitmapFactory.decodeResource(context.getResources(),
R.drawable.ic_launcher);
DisplayMetrics metrics = getContext()
.getResources()
.getDisplayMetrics();
int w = metrics.widthPixels;
int h = metrics.heightPixels;
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
// mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC))
// ;
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}
#Override
protected void onDraw(Canvas canvas) {
// mPath = new Path();
// canvas.drawPath(mPath, mPaint);
// canvas.drawColor(Color.TRANSPARENT);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
for (Path p : paths) {
canvas.drawPath(p, mPaint);
}
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
undonePaths.clear();
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
paths.add(mPath);
mPath = new Path();
}
public void onClickUndo() {
if (paths.size() > 0) {
undonePaths.add(paths.remove(paths.size() - 1));
invalidate();
} else {
}
// toast the user
}
public void onClickRedo() {
if (undonePaths.size() > 0) {
paths.add(undonePaths.remove(undonePaths.size() - 1));
invalidate();
} else {
}
// toast the user
}
public boolean onTouch(View arg0, MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
As user603125 says, currently you only have one paint object and you paint all paths with that paint. Remember that in onDraw you draw all paths anew every time.
To solve this, you'll have to keep track of the color to use by every path, e.g. in a map and do something like so:
private Map<Path, Color> mPathColors = new HashMap<Path, Color>(); // map for path colors
private Color mCurrentColor; // color to paint current path with (has to be set somewhere)
...
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
for (Path p : paths) {
mPaint.setColor(mPathColors.get(p);
canvas.drawPath(p, mPaint);
}
mPaint.setColor(mCurrentColor);
canvas.drawPath(mPath, mPaint);
}
And in touch_up() write the current color to the map like so:
private void touch_up() {
...
paths.add(mPath);
mPathColors.put(mPath, mCurrentColor);
...
}
You are using the Same paint object to draw the previous and as well as the current path.
#Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
mPaint.setColor(Color.YELLOW);
for (Path p : paths) {
canvas.drawPath(p, mPaint);
}
mPaint.setColor(Color.RED);
canvas.drawPath(mPath, mPaint);
}