android图片特效处理之图片叠加

家资是何物，积帙列梁梠。这篇文章主要讲述android图片特效处理之图片叠加相关的知识，希望能为你提供帮助。
这篇将讲到图片特效处理的图片叠加效果。跟前面一样是对像素点进行处理，可参照前面的android图像处理系列之七－－图片涂鸦，水印－图片叠加和android图像处理系列之六－－给图片添加边框（下）－图片叠加两篇文章，此篇所讲的与之前有一点区别。叠加原理是两张图片的像素点按透明度叠加，不会进行颜色过滤。叠加图片可以是JPG格式，跟前在一样，最好是放大assets目录。下面看效果图：

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+

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＝

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代码：
[java] view plain copy

/**
* 图片效果叠加
* @param bmp 限制了尺寸大小的Bitmap
* @return
*/
private Bitmap overlay(Bitmap bmp)
{
long start = System.currentTimeMillis();
int width = bmp.getWidth();
int height = bmp.getHeight();
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
// 对边框图片进行缩放
Bitmap overlay = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.rainbow_overlay);
int w = overlay.getWidth();
int h = overlay.getHeight();
float scaleX = width * 1F / w;
float scaleY = height * 1F / h;
Matrix matrix = new Matrix();
matrix.postScale(scaleX, scaleY);
Bitmap overlayCopy = Bitmap.createBitmap(overlay, 0, 0, w, h, matrix, true);
int pixColor = 0;
int layColor = 0;
int pixR = 0;
int pixG = 0;
int pixB = 0;
int pixA = 0;
int newR = 0;
int newG = 0;
int newB = 0;
int newA = 0;
int layR = 0;
int layG = 0;
int layB = 0;
int layA = 0;
final float alpha = 0.5F;
int[] srcPixels = new int[width * height];
int[] layPixels = new int[width * height];
bmp.getPixels(srcPixels, 0, width, 0, 0, width, height);
overlayCopy.getPixels(layPixels, 0, width, 0, 0, width, height);
int pos = 0;
for (int i = 0; i < height; i++)
{
for (int k = 0; k < width; k++)
{
pos = i * width + k;
pixColor = srcPixels[pos];
layColor = layPixels[pos];
pixR = Color.red(pixColor);
pixG = Color.green(pixColor);
pixB = Color.blue(pixColor);
pixA = Color.alpha(pixColor);
layR = Color.red(layColor);
layG = Color.green(layColor);
layB = Color.blue(layColor);
layA = Color.alpha(layColor);
newR = (int) (pixR * alpha + layR * (1 - alpha));
newG = (int) (pixG * alpha + layG * (1 - alpha));
newB = (int) (pixB * alpha + layB * (1 - alpha));
layA = (int) (pixA * alpha + layA * (1 - alpha));
newR = Math.min(255, Math.max(0, newR));
newG = Math.min(255, Math.max(0, newG));
newB = Math.min(255, Math.max(0, newB));
newA = Math.min(255, Math.max(0, layA));
srcPixels[pos] = Color.argb(newA, newR, newG, newB);
}
}
bitmap.setPixels(srcPixels, 0, width, 0, 0, width, height);
long end = System.currentTimeMillis();
Log.d("may", "overlayAmeliorate used time="+(end - start));
return bitmap;
}