checkin-mask-view

Android Bitmap PorterDuffXfermode One of Uses

使用PorterDuffXfermode-PorterDuff.Mode.SRC_IN 模式做的一个过渡效果。

原理是两张图片叠加的效果，一张合成的图以及对应的需要展示效果的Mask图片。

通过动画去操作Mask层级的图片，就可以实现该效果。

Preview

Core Practice

Assemble Bitmaps

...
 private Bitmap mMaskBitmap, mSrcBitmap, mWaterBitmap;
 private PorterDuffXfermode srcInMode = new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
 
 public void updateTodayCheckInUI(int convertDay, int mask, List<Integer> waterDrawables) {
        postDelayed(() -> {
            try {
                mSrcWidth = mSrcWidth > 0 ? mSrcWidth : getWidth();
                mSrcHeight = mSrcHeight > 0 ? mSrcHeight : getHeight();
                mSrcBitmap = BitmapHelper.scaleImage(BitmapHelper.decodeResource(getContext(), mask), mSrcWidth, mSrcHeight);
                mMaskBitmap = Bitmap.createBitmap(mSrcWidth, mSrcHeight, Bitmap.Config.ARGB_4444);

                mSrcRect = new Rect(0, 0, mSrcWidth, mSrcHeight);
                mDestRect = new Rect(0, 0, mSrcWidth, mSrcHeight);
                int currDay = convertDay % 9;
                mBeginHeight = mSrcHeight - (currDay <= 4 ? mSrcHeight / (currDay + 2) : 0);

                mCurrentTop = mBeginHeight;
                mDynamicRect = new Rect(0, mBeginHeight, mSrcWidth, mSrcHeight);

                if (convertDay == 9 || convertDay == 18 || convertDay == 27) {
                    invalidate();
                    return;
                }

                // begin compose water bitmaps
                if (waterDrawables.size() > 0) {
                    mWaterBitmap = Bitmap.createBitmap(mSrcWidth, mSrcHeight, Bitmap.Config.ARGB_4444);
                    Bitmap[] bitmaps = new Bitmap[waterDrawables.size()];
                    for (int i = 0; i < bitmaps.length; i++) {
                        bitmaps[i] = BitmapHelper.scaleImage(BitmapHelper.decodeResource(getContext(), waterDrawables.get(i)),            mSrcWidth, mSrcHeight);
                    }
                    mWaterBitmap = BitmapHelper.addWatermarks(mWaterBitmap, bitmaps);
                }
                invalidate();
            } catch (OutOfMemoryError e) {
                e.printStackTrace();
            }
        }, 100L);
    }

Draw Bitmap

 @Override
 protected void onDraw(Canvas canvas) {
      super.onDraw(canvas);
      if (mSrcBitmap == null || mMaskBitmap == null || mComplete)
          return;
      int saveLayerCount = canvas.saveLayer(0, 0, mSrcWidth, mSrcHeight, mBitPaint, Canvas.ALL_SAVE_FLAG);
      // draw mask bitmap & rect
      canvas.drawRect(mDynamicRect, mBitPaint);
      canvas.drawBitmap(mMaskBitmap, mSrcRect, mDestRect, mBitPaint);
      mBitPaint.setXfermode(srcInMode);
      //draw src bitmap
      canvas.drawBitmap(mSrcBitmap, mSrcRect, mDestRect, mBitPaint);
      mBitPaint.setXfermode(null);
      //draw water bitmap
      if (mWaterBitmap != null && !mWaterBitmap.isRecycled())
          canvas.drawBitmap(mWaterBitmap, 0, 0, mBitPaint);
      canvas.restoreToCount(saveLayerCount);
  }

Start invalidate

    public void start(OnMaskListener onMaskListener) {
        if (mMaskBitmap == null)
            return;
        ValueAnimator translationAnimator = ValueAnimator.ofFloat(mCurrentTop, 0).setDuration(400);
        translationAnimator.addUpdateListener(animation -> {
            float value = (float) animation.getAnimatedValue();
            mDynamicRect.top = (int) value;
            invalidate();
            if (value == 0) {
                if (onMaskListener != null) {
                    onMaskListener.onStartDrawMaskComplete();
                }
            }
        });
        translationAnimator.setDuration(1500);
        translationAnimator.start();
    }

About this project

整理的一个以前写的View 项目不能直接用 目前只做学习展示

Licence

Copyright 2018, junchenChow

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.