图片处理

图形旋转

Matrix matrix = new Matrix();
matrix.setRotate(15);
canvas.drawBitmap(bmp, matrix, paint);

消除锯齿
paint.setAntiAlias(true);   

指定圆心的旋转

matrix.setRotate(15,bmp.getWidth()/2,bmp.getHeight()/2);


Matrix matrix = new Matrix();
matrix.setRotate(15,bmp.getWidth()/2,bmp.getHeight()/2);
alteredBitmap = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(),matrix, false);
alteredImageView.setImageBitmap(alteredBitmap);

图像颜色处理

颜色矩阵
ColorMatrix cm = new ColorMatrix();
paint.setColorFilter(new ColorMatrixColorFilter(cm));
1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1 0
New Red Value = 1*128 + 0*128 + 0*128 + 0*0 + 0
New Blue Value = 0*128 + 1*128 + 0*128 + 0*0 + 0
New Green Value = 0*128 + 0*128 + 1*128 + 0*0 + 0
New Alpha Value = 0*128 + 0*128 + 0*128 + 1*0 + 0
ColorMatrix cm = new ColorMatrix();
cm.set(new float[] {
2, 0, 0, 0, 0,
0, 1, 0, 0, 0,
0, 0, 1, 0, 0,
0, 0, 0, 1, 0
});
paint.setColorFilter(new ColorMatrixColorFilter(cm));

更改图片饱和度

ColorMatrix cm = new ColorMatrix();
cm.setSaturation(0.5f);
paint.setColorFilter(new ColorMatrixColorFilter(cm));

图片合成

Bitmap drawingBitmap = Bitmap.createBitmap(bmp1.getWidth(),bmp1.getHeight(), bmp1.getConfig());
canvas = new Canvas(drawingBitmap);
paint = new Paint();
canvas.drawBitmap(bmp1, 0, 0, paint);
paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.MULTIPLY));
canvas.drawBitmap(bmp2, 0, 0, paint);

按指定path上绘制文字

Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setTextSize(20);
paint.setTypeface(Typeface.DEFAULT);
Path p = new Path();
p.moveTo(20, 20);
p.lineTo(100, 150);
p.lineTo(200, 220);
canvas.drawTextOnPath("Hello this is text on a path", p, 0, 0, paint);