public class MyView extends View{
Bitmap myBitmap;
Paint paint;
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
this.initBitmap();
}
public void initBitmap(){
paint = new Paint();
myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.img);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setAntiAlias(true);
paint.setColor(Color.WHITE);
paint.setTextSize(15);
canvas.drawBitmap(myBitmap, 10, 10, paint);
//Saves the current matrix and clip onto a private stack.
//Subsequent calls to translate,scale,rotate,skew,concat or clipRect,clipPath
//will all operate as usual, but when the balancing call to restore() is made,
//those calls will be forgotten, and the settings that existed before the save() will be reinstated(恢复).
//Returns:
//The value to pass to restoreToCount() to balance this save()
int i = canvas.save();
System.out.println("current count -- > " + i);
Matrix m1 = new Matrix();
m1.setTranslate(500, 10);
Matrix m2 = new Matrix();
m2.setRotate(15);
Matrix m3 = new Matrix();
m3.setConcat(m1, m2);
m1.setScale(0.8f, 0.8f);
m2.setConcat(m3, m1);
canvas.drawBitmap(myBitmap, m2, paint);
//This call balances a previous call to save(), and is used to
//remove all modifications to the matrix/clip state since the last save call.
//It is an error to call restore() more times than save() was called.
canvas.restore();
int j = canvas.save();
System.out.println("current count -- > " + j);
paint.setAlpha(180);
m1.setTranslate(200, 100);
m2.setScale(1.3f, 1.3f);
m2.setConcat(m1, m2);
canvas.drawBitmap(myBitmap, m3, paint);
//Restores the paint to its default settings.
paint.reset();
canvas.restore();
paint.setTextSize(40);
paint.setColor(Color.BLUE);
canvas.drawText("图片的宽度:" + myBitmap.getWidth(), 150, 220, paint);
canvas.drawText("图片的高度:" + myBitmap.getHeight(), 150, 300, paint);
paint.reset();
}
}
效果图：
