Android obtains the brightness of an image.

 

Problem: there is now a background control AA (such as ImageView, LinearLayout, ViewGroup, or other controls ), now, if you want to place another control BB on this control to display the current status (for example, the screen indicator in Launcher), the background of the control AA can be dynamically modified in the program, if the background of AA is similar to the background color of BB, the effect of BB is not obvious. It is not clear that the current AA status is displayed.

 

Solution: Obtain the RGB value of the AA background, calculate the brightness of the current screen based on the RGB value, and create two sets of pictures for BB, which are brighter and darker, respectively, if the brightness value of AA is relatively high, BB uses a darker image. If the brightness value of AA is relatively low, BB uses a brighter image, so that BB plays a significant role.

 

The Code is as follows:

 

 

Drawable localDrawable = wpm. getDrawable ();

Bitmap bitmap = Bitmap

. CreateBitmap (

LocalDrawable. getIntrinsicWidth (),

LocalDrawable. getIntrinsicHeight (),

LocalDrawable. getOpacity ()! = PixelFormat. OPAQUE? Bitmap. Config. ARGB_8888

: Bitmap. Config. RGB_565 );

Canvas canvas = new Canvas (bitmap );

LocalDrawable. setBounds (0, 0, localDrawable. getIntrinsicWidth (),

LocalDrawable. getIntrinsicHeight ());

LocalDrawable. draw (canvas );

 

Int localWidth = this. getWindowManager (). getdefadisplay display (). getWidth ();

Int y [] = {0, 4, 9, 13, 18, 23, 28, 33, 38, 43, 48 };

Int x [] = {0, localWidth/8, localWidth * 2/8, localWidth * 3/8,

LocalWidth * 4/8, localWidth * 5/8, localWidth * 6/8,

LocalWidth * 7/8, localWidth };

 

Int r;

Int g;

Int B;

Int number = 0;

Double bright = 0;

Integer localTemp;

For (int I = 0; I <x. length; I ++ ){

For (int j = 0; j <y. length; j ++ ){

Number ++;

LocalTemp = (Integer) bitmap. getPixel (x [I], y [j]);

R = (localTemp | 0xff00ffff)> 16 & 0x00ff;

G = (localTemp | 0xffff00ff)> 8 & 0x0000ff;

B = (localTemp | 0xffffff00) & 0x0000ff;

 

Bright = bright + 0.299 * r + 0.587 * g + 0.114 * B;

Log. I ("xiao", "bright =" + bright );

}

}

LocalDrawable = null;

Bitmap = null;

Bright = (int) (bright/number );

 

Code explanation: Get the Drawable object and convert it to Bitmap (the Drawable object does not return its RGB value function, Bitmap can return the RGB value of a certain point bitmap. getPixel), get the RGB value of some specific points in the current region, bitmap. getPixel returns the ARGB value. The R, G, and B values are obtained through the shift operation. The brightness is calculated using the brightness = 0.229 × R + 0.587 * G + 0.114 * B, add the brightness values of all vertices and obtain an average value. If the value is greater than 128, the image is brighter. If the value is smaller than 128, the image is darker.

 

From: column xiaoxiaobian3310903