android 12 launcher icon背景透明

客户需求要求launcher上面的应用icon为背景透明的，Android sdk26后应用icon使用的是adaptive-icon图标；

Android 11 上没有做严格的验证，直接在解析 background 属性时continue就可以了；

Index: frameworks/base/graphics/java/android/graphics/drawable/AdaptiveIconDrawable.java
===================================================================  处理ICON图标透明
--- frameworks/base/graphics/java/android/graphics/drawable/AdaptiveIconDrawable.java   (revision 21510)
+++ frameworks/base/graphics/java/android/graphics/drawable/AdaptiveIconDrawable.java   (working copy)
@@ -358,7 +358,8 @@
         }
         if (mLayersShader == null) {
             mCanvas.setBitmap(mLayersBitmap);
-            mCanvas.drawColor(Color.BLACK);
+            // mCanvas.drawColor(Color.BLACK);
+            mCanvas.drawColor(Color.TRANSPARENT);
             for (int i = 0; i < mLayerState.N_CHILDREN; i++) {
                 if (mLayerState.mChildren[i] == null) {
                     continue;
@@ -482,7 +483,8 @@
             String tagName = parser.getName();
             if (tagName.equals("background")) {
                 childIndex = BACKGROUND_ID;
+                continue;
            } else  if (tagName.equals("foreground")) {
                 childIndex = FOREGROUND_ID;
             } else {
                 continue;
Index: packages/apps/Launcher3/src/com/android/launcher3/folder/PreviewBackground.java
===================================================================   处理文件夹图标透明
--- packages/apps/Launcher3/src/com/android/launcher3/folder/PreviewBackground.java (revision 21510)
+++ packages/apps/Launcher3/src/com/android/launcher3/folder/PreviewBackground.java (working copy)
@@ -221,7 +221,8 @@
     }
 
     public int getBgColor() {
-        int alpha = (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+        // int alpha = (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+        int alpha = 0;
         return setColorAlphaBound(mBgColor, alpha);
     }
 
@@ -420,7 +421,8 @@
     }
 
     public int getBackgroundAlpha() {
-        return (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+        // return (int) Math.min(MAX_BG_OPACITY, BG_OPACITY * mColorMultiplier);
+        return 0;
     }
 
     public float getStrokeWidth() {

12上做非空验证，会报空指针NullPointerException

2022-08-13 15:41:19.899 7604-7604/com.android.launcher3 W/UnsafeUtil: platform method missing - proto runtime falling back to safer methods: java.lang.NoSuchMethodException: sun.misc.Unsafe.copyMemory [class java.lang.Object, long, class java.lang.Object, long, long]
2022-08-13 15:41:19.907 7604-7623/com.android.launcher3 E/LoaderTask: Desktop items loading interrupted
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.graphics.drawable.ColorDrawable.setColor(int)' on a null object reference
        at com.android.launcher3.icons.BaseIconFactory.normalizeAndWrapToAdaptiveIcon(BaseIconFactory.java:312)
        at com.android.launcher3.icons.BaseIconFactory.createBadgedIconBitmap(BaseIconFactory.java:217)
        at com.android.launcher3.icons.BaseIconFactory.createBadgedIconBitmap(BaseIconFactory.java:192)
        at com.android.launcher3.icons.BaseIconFactory.createBadgedIconBitmap(BaseIconFactory.java:185)
        at com.android.launcher3.icons.BaseIconFactory.createBadgedIconBitmap(BaseIconFactory.java:180)
        at com.android.launcher3.icons.LauncherActivityCachingLogic.loadIcon(LauncherActivityCachingLogic.java:60)
        at com.android.launcher3.icons.LauncherActivityCachingLogic.loadIcon(LauncherActivityCachingLogic.java:31)
        at com.android.launcher3.icons.cache.BaseIconCache.cacheLocked(BaseIconCache.java:327)
        at com.android.launcher3.icons.IconCache.getTitleAndIcon(IconCache.java:300)
        at com.android.launcher3.icons.IconCache.getTitleAndIcon(IconCache.java:194)
        at com.android.launcher3.model.LoaderCursor.getAppShortcutInfo(LoaderCursor.java:291)
        at com.android.launcher3.model.LoaderTask.loadWorkspace(LoaderTask.java:538)
        at com.android.launcher3.model.LoaderTask.loadWorkspace(LoaderTask.java:313)
        at com.android.launcher3.model.LoaderTask.run(LoaderTask.java:197)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loopOnce(Looper.java:201)
        at android.os.Looper.loop(Looper.java:288)
        at android.os.HandlerThread.run(HandlerThread.java:67)

所以不在解析的时候过滤，而是在draw()中做下过滤不绘制background；

Index: java/android/graphics/drawable/AdaptiveIconDrawable.java
     @Override
@@ -358,9 +359,10 @@
         }
         if (mLayersShader == null) {
             mCanvas.setBitmap(mLayersBitmap);
-            mCanvas.drawColor(Color.BLACK);
+            //mCanvas.drawColor(Color.BLACK);
+            mCanvas.drawColor(Color.TRANSPARENT);
             for (int i = 0; i < mLayerState.N_CHILDREN; i++) {
-                if (mLayerState.mChildren[i] == null) {
+                if (mLayerState.mChildren[i] == null || i== BACKGROUND_ID) {
                     continue;
                 }
                 final Drawable dr = mLayerState.mChildren[i].mDrawable;