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POHow to draw lots of bitmaps on screen in an Android game without slow performance
 

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  1. POHow to draw lots of bitmaps on screen in an Android game without slow performance
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    <p>I want to make a tile based game for android. At the moment I am drawing each tile as a separate bitmap. I have a big for loop that reads from a string and draws different tiles depending on what character it finds to draw the level.</p> <p>I have allowed the user to scroll the screen using scrolling gestures. However the game is too slow. It takes a long time to update the screen after the user scrolls. I presume this is because it has to draw each tile's bitmap individually.</p> <p>What would be a faster way to draw the level? I was thinking I could merge all the tiles into one bitmap. But I don't know how to do this. Any ideas?</p> <p>Anyway here is my code so you can see the problem:</p> <pre><code>package org.example.tutorial2d; import android.app.Activity; import android.os.Bundle; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.GestureDetector.OnGestureListener; import org.example.tutorial2d.Panel; public class Tutorial2D extends Activity implements OnGestureListener { GestureDetector gestureScanner; Panel main; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); gestureScanner = new GestureDetector(this); //requestWindowFeature(Window.FEATURE_NO_TITLE); main = new Panel(this); setContentView(main); } @Override public boolean onTouchEvent(MotionEvent me) { return gestureScanner.onTouchEvent(me); } @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { main.handleScroll(distanceX,distanceY); return true; } //////////////////// /////////////////// ////////////////// @Override public boolean onDown(MotionEvent e) { return true; } @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { return true; } @Override public void onLongPress(MotionEvent e){ } @Override public void onShowPress(MotionEvent e) { } @Override public boolean onSingleTapUp(MotionEvent e) { return true; } //////////////////// /////////////////// ////////////////// } </code></pre> <p>And the class that does all the work:</p> <pre><code>package org.example.tutorial2d; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.drawable.Drawable; import android.util.Log; import android.view.View; import org.example.tutorial2d.Point; public class Panel extends View { private int scrollX = 0; private int scrollY = 0; public Panel(Context context) { super(context); } @Override public void onDraw(Canvas canvas) { /*Bitmap scratch; //Drawable scratch; //scratch = getContext().getResources().getDrawable( // R.drawable.icon); canvas.drawColor(Color.BLACK); //scratch.draw(canvas); int origin = 0; scratch = BitmapFactory.decodeResource(getResources(), R.drawable.horizontal5); canvas.drawBitmap(scratch, origin, origin, null); int width = scratch.getWidth(); int height = scratch.getHeight(); scratch = BitmapFactory.decodeResource(getResources(), R.drawable.room4entrynesw3x3); canvas.drawBitmap(scratch, origin + width, origin - 32, null); */ String sucide_mission = " wwwww\n" + " wfffw\n" + " wfffw\n" + " wfffw\n" + " wwfww\n" + " wfw\n" + " wfw\n" + " wfw\n" + " wwwwwwwfwwwwwfw\n" + " wfffffffffffffw\n" + " wfwwwwwfwwwwwfw\n" + " wwwww wfw wfw wfw\n" + "wwwwwwfffwwwwwfwwwwwfwwwwwfw\n" + "fffffffffffffffffffffffffffw\n" + "wwwwwwfffwwwwwwwwwwwfwwwwwfw\n" + " wwfww wfw\n" + " wfw wfw\n" + " wfw wfw\n" + " wfw wfw\n" + " wfw wfw\n" + " wwfww wfw\n" + " wfffwwfw fff\n" + " wffffffw www\n" + " wfffwwfw\n" + " wwwww"; canvas.drawColor(Color.BLACK); int x = 0, y = 0; for (int i = 0; i &lt; sucide_mission.length(); i++) { Bitmap tileImage; char tile = sucide_mission.charAt(i); Log.d("Draw tiles", Character.toString(tile) + " " + x + "," + y); switch (tile) { case 'w': if (x &lt; tileImage = BitmapFactory.decodeResource(getResources(), R.drawable.walla); canvas.drawBitmap(tileImage, x - scrollX, y - scrollY, null); x += 32; break; case 'f': tileImage = BitmapFactory.decodeResource(getResources(), R.drawable.floore); canvas.drawBitmap(tileImage, x - scrollX, y - scrollY, null); x += 32; break; case ' ': x += 32; break; case '\n': y += 32; x = 0; break; } } //canvas.drawBitmap(adapt, 0, 0, paint); //canvas.drawBitmap(corner, origin -scrollX , origin -scrollY, paint); } public void handleScroll(float distX, float distY) { // X-Axis //////////////////////////////// if(distX &gt; 6.0) { if(scrollX &lt; 460) { scrollX += 30; } } else if(distX &lt; -6.0) { if(scrollX &gt;= 30) { scrollX -= 30; } } //////////////////////////////////////////// // Y-AXIS ////////////////////////////////// if(distY &gt; 6.0) { if(scrollY &lt; 100) { scrollY += 30; } } else if(distY &lt; -6.0) { if(scrollY &gt;= 30) { scrollY -= 30; } } //////////////////////////////////////////// if((scrollX &lt;= 480) &amp;&amp; (scrollY &lt;= 120)) { //adapt = Bitmap.createBitmap(bmp, scrollX, scrollY, 320, 480); invalidate(); } } } </code></pre>
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