Question

So I’ve got this nice Android game (a snake-clone with animations), doing the final testing, when BAM! My second testing device (Nexus 1, HTC Magic was my 1.) flickers when drawing.
Does anyone know why this code won’t work correctly with the Nexus 1?

public void draw(Canvas canv) {
int count = 0;
isHead = false;
for (int i = 0; i < SPACES; i++) {
    if (mDrawSpaces[i]) {
    count++;
    if (count == SPACES - 1) {
        setDrawSpacesToFalse();
        if (bmp != null)
        super.drawPlaceable(canv);
    }
    } else {
    mDrawSpaces[i] = true;
    return;
    }
}
}

I have a list of Birds (Birds / UFOs / others) with SPACES (4) times as many elements which are being drawn on the screen. So I thought to myself, instead of calculating the rotation and scale of the pictures for every Bird, I merely have 3 placeholders between the Birds which each have a picture to be drawn once they’re set to visible. These pictures are generated by the first Bird:

public void drawHead(Canvas canv) {
    //calculate the rotation & mirroring of the picture
    super.drawPlaceable(canv);
        //generate the pics for smaller birds following it
    mat.preScale((float) 0.6, (float) 0.6);
    this.bmp = Bitmap.createBitmap(SPRITESHEET, Bird.mCurFrame
        * BIG_W[mUseBird], 0, BIG_W[mUseBird], BIG_H[mUseBird],
        mat, true);
}

Any ideas? Is my draw(Canvas) method wrong in some part?

EDIT: I don’t know why, I don’t know how, but this afternoon when I tested it again, it magically worked…

Answer 1

I can see you are using matrix to scale – another option would be to use

canvas.DrawBitmap(spriteSheet, fromRect, toRect, paint);

Where toRect should be a Rect class of any size, in this way you would create no bitmap objects when drawing game frames. The piant should have filter bitmap enabled.

To rotate you would have to use:

canvas.save();
canvas.rotate(spriteAngle,spriteCenterX, spriteCenterY);
canvas.DrawBitmap(spriteSheet, fromRect, toRect, paint);
canvas.restore();

This is a fast enough code for many 2D games, though not as fast and powerful as OpenGL.