在Android開發過程中，一定會用到帶圖片的按鈕，傳統方法是UI出兩張圖，一張正常狀態，一張按下狀態。其實多數時候，按鈕按下的效果就是正常狀態的圖片改變一下亮度，廢話少說，直接上代碼。
<code>import android.content.Context;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.Canvas;import android.graphics.ColorMatrix;import android.graphics.ColorMatrixColorFilter;import android.graphics.Paint;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.graphics.drawable.StateListDrawable;import android.util.AttributeSet;import android.widget.Button;/** * 單張圖片實現按下效果的Button * * @author CharlesRich * @email 18602438878@qq.com * @mobile 18602438878 * @create 2020-02-10 18:55 */public class ImageButton extends Button { private Context context; public ImageButton(Context context) { super(context); this.context = context; init(); } public ImageButton(Context context, AttributeSet attrs) { super(context, attrs); this.context = context; init(); } public ImageButton(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); this.context = context; init(); } private void init() { setBackgroundDrawable(newSelector()); } /** * 傳入改變亮度前的bitmap，返回改變亮度後的bitmap * * @param bitmap * @return */ private Drawable changeBrightnessBitmap(Bitmap bitmap) { Bitmap bmp = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888); int brightness = 60 - 127; ColorMatrix cMatrix = new ColorMatrix(); cMatrix.set(new float[]{1, 0, 0, 0, brightness, 0, 1, 0, 0, brightness,/** 改變亮度 */ 0, 0, 1, 0, brightness, 0, 0, 0, 1, 0}); Paint paint = new Paint(); paint.setColorFilter(new ColorMatrixColorFilter(cMatrix)); Canvas canvas = new Canvas(bmp); /** 在Canvas上繪製一個Bitmap */ canvas.drawBitmap(bitmap, 0, 0, paint); return new BitmapDrawable(bmp); } /** * 設置Selector */ private StateListDrawable newSelector() { StateListDrawable bg = new StateListDrawable(); Drawable normal = getBackground(); Drawable pressed = changeBrightnessBitmap(((BitmapDrawable) getBackground()).getBitmap()); /** View.PRESSED_ENABLED_STATE_SET */ bg.addState(new int[]{android.R.attr.state_pressed, android.R.attr.state_enabled}, pressed); /** View.ENABLED_STATE_SET */ bg.addState(new int[]{android.R.attr.state_enabled}, normal); /** View.EMPTY_STATE_SET */ bg.addState(new int[]{}, normal); return bg; }}/<code>