Develop Reference

Android PathShape not drawing path (Canvas/Java/Android Studio)

I'm just trying to draw a basic triangle in Android Studio but nothing is showing up when I run the program. This is my first Android program so I don't really know what I'm doing. What is wrong with it?
public class CustomDrawableView extends View {
private ShapeDrawable mDrawable;
public CustomDrawableView(Context context, Display display) {
super(context);
Point size = new Point();
display.getSize(size);
int screenWidth = size.x;
int screenHeight = size.y;
int pathWidth = screenWidth / 6;
int startWidth = screenWidth / 10;
Path path = new Path();
path.moveTo(startWidth, 0);
path.moveTo(startWidth, screenHeight / 5);
path.moveTo(screenWidth / 5, screenHeight / 5);
path.close();
mDrawable = new ShapeDrawable(new PathShape(path, screenWidth, screenHeight));
mDrawable.setDither(true);
int color = Color.parseColor("#ff74AC23");
mDrawable.getPaint().setColor(color);
mDrawable.setBounds(0, 0 , screenWidth, screenHeight);
}
protected void onDraw(Canvas canvas) {
mDrawable.draw(canvas);
}
}
public class MainActivity extends AppCompatActivity {
CustomDrawableView mCustomDrawableView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Display display = getWindowManager().getDefaultDisplay();
mCustomDrawableView = new CustomDrawableView(this, display);
setContentView(mCustomDrawableView);
}
}

Android : moving bmp leaving a trail ( Surface View and Canvas )

I was trying to animate a sprite for an android app and i've encounter a small problem. I'm drawing on a surfaceView that i add on top of already existing layouts. On this surfaceView, i wanted to animate few sprites so they would walk along a path.
So this is the result i'm facing right now :
The walking sprite is leaving a trail. So i decided to google this problem and apparently i had to clear the canvas first before drawing on it.
This was my onDraw method before :
public void onDraw(Canvas canvas) {
update();
int srcX = currentFrame * width;
int srcY = directionX * height;
Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);
Rect dst = new Rect(x, y, x + width, y + height);
canvas.drawBitmap(bmp, src, dst, null);
}
And this was my onDraw method after
public void onDraw(Canvas canvas) {
canvas.drawRGB(0, 0, 0);
update();
int srcX = currentFrame * width;
int srcY = directionX * height;
Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);
Rect dst = new Rect(x, y, x + width, y + height);
canvas.drawBitmap(bmp, src, dst, null);
}
So i now have this as a result
which is great because it leaves no more trail BUT i cant see the layouts underneath. Is there anyway i can get the best of both world ? I thought clearing the canvas would work but it obviously doesnt not work as expected.
I'll post my code below
SurfaceView :
public class MonsterView extends SurfaceView {
private Bitmap monsterImg;
private SurfaceHolder holder;
private MonsterThread mainThread;
private Sprite monsterSprite;
private int x;
private int xSpeed = 1;
public MonsterView(Context context) {
super(context);
this.mainThread = new MonsterThread(this);
this.x = 0;
holder = getHolder();
holder.setFormat(PixelFormat.TRANSPARENT);
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceCreated(SurfaceHolder holder) {
mainThread.setRunning(true);
mainThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
mainThread.setRunning(false);
while (retry) {
try {
mainThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
});
setZOrderOnTop(true);
monsterImg = BitmapFactory.decodeResource(getResources(), R.drawable.fire);
monsterSprite = new Sprite(this,monsterImg);
}
#Override
public void onDraw(Canvas canvas) {
if (x == getWidth() - monsterImg.getWidth()) {
xSpeed = -1;
}
if (x == 0) {
xSpeed = 1;
}
x = x + xSpeed;
monsterSprite.onDraw(canvas);
}
Thread :
public class MonsterThread extends Thread {
private MonsterView monsterSurface;
private boolean running;
static final long FPS = 35;
public MonsterThread(MonsterView monsterSurface){
this.monsterSurface = monsterSurface;
this.running = false;
}
#Override
public void run() {
long ticksPS = 1000 / FPS;
long startTime;
long sleepTime;
while(running){
Canvas c = null;
startTime = System.currentTimeMillis();
try{
c = monsterSurface.getHolder().lockCanvas();
synchronized (monsterSurface.getHolder()){
monsterSurface.onDraw(c);
}
} finally {
if( c!= null){
monsterSurface.getHolder().unlockCanvasAndPost(c);
}
}
sleepTime = ticksPS-(System.currentTimeMillis() - startTime);
try {
if(sleepTime > 0)
sleep(sleepTime);
else
sleep(10);
} catch (Exception e){}
}
}
public MonsterView getMonsterSurface() {
return monsterSurface;
}
public void setMonsterSurface(MonsterView monsterSurface) {
this.monsterSurface = monsterSurface;
}
public boolean isRunning() {
return running;
}
public void setRunning(boolean running) {
this.running = running;
}
Sprite :
public class Sprite {
private static final int BMP_ROWS = 4;
private static final int BMP_COLUMNS = 3;
private int x = 0;
private int y = 0;
private int xSpeed = 5;
private MonsterView monsterView;
private Bitmap bmp;
private int currentFrame = 0;
private int width;
private int height;
private int directionX;
public Sprite(MonsterView monsterView, Bitmap bmp) {
this.monsterView = monsterView;
this.bmp=bmp;
this.width = bmp.getWidth() / BMP_COLUMNS;
this.height = bmp.getHeight() / BMP_ROWS;
this.directionX = 2;
}
private void update() {
if (x > monsterView.getWidth() - width - xSpeed) {
xSpeed = -5;
directionX = 1;
}
if (x + xSpeed < 0) {
xSpeed = 5;
directionX = 2;
}
x = x + xSpeed;
currentFrame = ++currentFrame % BMP_COLUMNS;
Log.d("test", ""+currentFrame);
}
public void onDraw(Canvas canvas) {
update();
int srcX = currentFrame * width;
int srcY = directionX * height;
Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);
Rect dst = new Rect(x, y, x + width, y + height);
canvas.drawBitmap(bmp, src, dst, null);
}

You're using setZOrderOnTop(), which is putting the Surface part of the SurfaceView on a layer above everything else. (By default, it's a separate layer below everything else.) When you clear it with canvas.drawRGB(0, 0, 0) you're setting the entire layer to opaque black, which is going to obscure the View layer beneath it.
If instead you clear it to transparent black, with canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR), you should get the results you want.
FWIW, you shouldn't override onDraw() if you're only drawing on the Surface. The onDraw() method is called by the View hierarchy to draw on the View part of the SurfaceView. If something manages to invalidate the SurfaceView's View, your onDraw() will be called, and you'll end up with a character sprite on the View layer. (Depending on your layout this may not be visible.) Just give the method a different name.

There are a number of ways to handle this, but generally, the way to do this is by maintaining a background layer (which is just another image), and sprite layers. Instead of clearing, at each frame you blit (copy) your background onto the surface (which erases everything), then you blit your sprites.

So you're going to have to draw the background bitmap onto the surface first before drawing your sprite. Right now you're drawing black which is covering your background layouts.
Alternatively you might be able to do canvas.drawRect with a Paint with paint.setColor to Color.Transparent.

How to design a simple game map in Android?

I'm making a very very simple game in Android, and I'm not using OpenGL or any other libraries, just Java!
Now I'm stuck in designing my map...
I want to design something like this:
(Those lines should consider as walls and players can't get out of them)
How to design something like this using XML only? Or I should start using Unity3D?

This isn't done with xml, but you neither need any libraries.
public class Background extends View {
private static final int BORDER_WIDTH = 2; //in px
private int[] points; //2n = x, 2n+1 = y
public Background(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for(Drawable drawable : drawBackground()){
drawable.draw(canvas);
}
}
private Drawable[] drawBackground() {
Drawable[] drawables = new Drawable[2];
int width = getWidth();
int height = getHeight();
int corner = width / 4;
//draw border
Path path = new Path();
path.moveTo(0, corner);
path.lineTo(corner, 0);
path.lineTo(width, 0);
path.lineTo(width, height - corner);
path.lineTo(width - corner, height);
path.lineTo(0, height);
path.close();
drawables[0] = new ShapeDrawable(new PathShape(path, width, height));
drawables[0].setBounds(0, 0, width, height);
//draw inside the border
points = {
BORDER_WIDTH, corner,
corner, BORDER_WIDTH,
width - BORDER_WIDTH, BORDER_WIDTH,
width - BORDER_WIDTH, height - corner,
width - corner, height - BORDER_WIDTH,
BORDER_WIDTH, height - BORDER_WIDTH
}
path = new Path();
path.moveTo(points[0], points[1]);
for (int i = 2, i < points.length, i++) {
path.lineTo(points[i], points[++i]);
}
path.close();
ShapeDrawable shapeDrawable = new ShapeDrawable(new PathShape(path, width, height));
shapeDrawable.getPaint().setColor(Color.rgb(238, 238, 238));
shapeDrawable.setBounds(0, 0, width, height);
drawables[1] = shapeDrawable;
return drawables;
}
public Point[] getPoints() {
return points;
}
}
The result:

Java - Making bitmaps scale to your screen size?

I am creating an app and want my ui to scale with the phone. I am importing bitmaps into a canvas and drawing them as follows:
public class MainMenu extends View {
private RectF titleBounds, playBounds, scoreBounds, soundBounds, creditBounds;
private Paint titlePaint, playPaint;
private boolean playClick = false, startPlay = false, scoreClick = false, startScore = false, soundClick = false, startSound = false, creditsClick = false, startCredits = false;
public Bitmap play;
public Bitmap playGlow;
public Bitmap sound;
public Bitmap soundGlow;
public int screenWidth, screenHeight;
public MainMenu(Context context) {
super(context);
titleBounds = new RectF();
playBounds = new RectF();
scoreBounds = new RectF();
soundBounds = new RectF();
creditBounds = new RectF();
titlePaint = new Paint();
playPaint = new Paint();
play = BitmapFactory.decodeResource(getResources(), R.drawable.play);
playGlow = BitmapFactory.decodeResource(getResources(), R.drawable.playglow);
sound = BitmapFactory.decodeResource(getResources(), R.drawable.sound);
soundGlow = BitmapFactory.decodeResource(getResources(), R.drawable.soundglow);
// Get window size and save it to screenWidth and screenHeight.
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
Point size = new Point();
display.getSize(size);
screenWidth = size.x;
screenHeight = size.y;
}
#Override protected void onDraw(Canvas canvas) {
ViewGroup parent = (ViewGroup)getParent();
playBounds.set(screenWidth / 2 - play.getWidth() / 2, screenHeight * 1/3 - play.getHeight() / 2, playBounds.left + play.getWidth(), playBounds.top + play.getHeight());
soundBounds.set(scoreBounds.centerX() - sound.getWidth() / 2, scoreBounds.bottom + 10, soundBounds.left + sound.getWidth(), soundBounds.top + sound.getHeight());
The problem is theres nothing to scale the image to fit the phone, it just reads the x and y size of the image I import. What method is there for scaling images?

Use the createScaledBitmap of the Bitmap class
bitmap = Bitmap.createScaledBitmap(bitmap, scaledWidth, scaledHeight, true);
It will scale your bitmap but not greater than the width and height that is because it can cause blurriness to your bitmap.
documentation:
Creates a new bitmap, scaled from an existing bitmap, when possible.
If the specified width and height are the same as the current width and height of the source bitmap,
the source bitmap is returned and no new bitmap is created.
for full screen
bitmap = Bitmap.createScaledBitmap(bitmap, screenWidth , screenHeight , true);

How can I center this rectangle and image in the y axis?

So far, my image starts at 0,0 and scales properly. There is a black bar under it. How can I align it so that it is centered along the y, with a black bar above and below the image?
edit: also, what are "this.getWidth(), this.getHeight()" referring to when I make the object "dest" - the width of mBitmap? The documentation does say they represent the width of the view, I just want to make sure I'm correct in thinking that is it mBitmap.
public class SpotGameActivity extends Activity {
private Bitmap mBitmap;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.dpi2b);
setContentView(new BitMapView(this, mBitmap));
}
class BitMapView extends View {
Bitmap mBitmap = null;
public BitMapView(Context context, Bitmap bm) {
super(context);
mBitmap = bm;
}
#Override
protected void onDraw(Canvas canvas) {
//DisplayMetrics metrics = new DisplayMetrics();
//getWindowManager().getDefaultDisplay().getMetrics(metrics);
// called when view is drawn
Paint paint = new Paint();
paint.setFilterBitmap(true);
// The image will be scaled so it will fill the width, and the
// height will preserve the image’s aspect ration
float aspectRatio = ((float) mBitmap.getWidth()) / mBitmap.getHeight();
Rect dest = new Rect(0, 0, this.getWidth(),(int) (this.getWidth() / aspectRatio));
String AR = Double.toString(aspectRatio);
canvas.drawBitmap(mBitmap, null, dest, paint);
Toast.makeText(SpotGameActivity.this, AR, Toast.LENGTH_SHORT).show();
}
I've now gotten the difference between the view size and image size. I've divided the difference by 2 but now, my image is align to the bottom of the screen rather than the middle of the y-axis. any tips?:
#Override
protected void onDraw(Canvas canvas) {
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int scrHeight = this.getHeight();
String sH = Integer.toString(scrHeight);
Log.v(TAG, "scrHeight =" + sH );
int imgHeight= mBitmap.getHeight();
String iH = Integer.toString(imgHeight);
Log.v(TAG, "imgHeight =" + iH );
int diff = scrHeight - imgHeight;
String dif = Integer.toString(diff);
Log.v(TAG, "diff =" + dif );
int dvd= diff/2;
// called when view is drawn
Paint paint = new Paint();
paint.setFilterBitmap(true);
// The image will be scaled so it will fill the width, and the
// height will preserve the image’s aspect ration
float aspectRatio = ((float) mBitmap.getWidth()) / mBitmap.getHeight();
Rect dest = new Rect(0, dvd, this.getWidth(),(int) (this.getWidth() / aspectRatio)+dvd);
String AR = Double.toString(dvd);
canvas.drawBitmap(mBitmap, null, dest, paint);
Toast.makeText(SpotGameActivity.this, AR, Toast.LENGTH_SHORT).show();