android图片特效处理之图片叠加

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：


+

＝



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;

}

叠加的边框图片还是大点比较好，也要控制被叠加图片大小。alpha变量值可以根据需求修改，建议还是大于0.5比较好，不然原图会看不清楚。