android 通過修改圖片畫素實現CircleImageView
阿新 • • 發佈:2019-04-13
CircleImageView實現方法有很多種,各有優缺點,因此需要按照不同的場景使用。我們今天使用修改圖片畫素的方法實現CircleImageView,主要知識點無非是勾股定理和點到圓形的距離。
素材圖片:
效果如下:
1、clipPath裁剪畫布
該方法支援的最小版本是Android 4.3(API Level 18),方便快捷,但是不支援硬體加,此外也存在Path既有的缺點,不支援抗鋸齒。
@Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pic); mPath = new Path(); mPath.addCircle(mBitmap.getWidth() / 2, mBitmap.getHeight() / 2, mBitmap.getWidth() / 2, Path.Direction.CCW); canvas.clipPath(mPath); canvas.drawBitmap(mBitmap, 0, 0, paint); }
2、使用PorterDuffXfermode
PorterDuffXfermode是Android主流的圖片合成工具,支援模式多,穩定性強,效果好,質量高,支援抗鋸齒備受廣大開發者喜愛,可以說是很多應用開發的首選。缺點是難度學習有些高,另外比較佔記憶體。
/** * 繪製圓形圖片 * */ @Override protected void onDraw(Canvas canvas) { Drawable drawable = getDrawable(); if (null != drawable) { Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap(); Bitmap b = getCircleBitmap(bitmap); final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight()); final Rect rectDest = new Rect(0,0,getWidth(),getHeight()); paint.reset(); canvas.drawBitmap(b, rectSrc, rectDest, paint); } else { super.onDraw(canvas); } } /** * 獲取圓形圖片方法 * @param bitmap * @param pixels * @return Bitmap */ private Bitmap getCircleBitmap(Bitmap bitmap) { Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888); Canvas canvas = new Canvas(output); final int color = 0xff424242; final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight()); paint.setAntiAlias(true); canvas.drawColor(Color.TRANSPARENT); paint.setColor(color); int x = bitmap.getWidth(); canvas.drawCircle(x / 2, x / 2, x / 2, paint); paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); canvas.drawBitmap(bitmap, rect, rect, paint); return output; }
4、設定畫筆Paint的Shader,然後用該畫筆繪製圓形圖片
該方法是Glide和picasso使用的方法,用法簡單便捷,佔內佔有率處於中等水平。
@Override protected void onDraw(Canvas canvas) { Drawable drawable = getDrawable(); if (null != drawable) { Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap(); Bitmap b = transform(bitmap); final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight()); final Rect rectDest = new Rect(0,0,getWidth(),getHeight()); paint.reset(); canvas.drawBitmap(b, rectSrc, rectDest, paint); } else { super.onDraw(canvas); } } public Bitmap transform(Bitmap source) { int size = Math.min(source.getWidth(), source.getHeight()); int x = (source.getWidth() - size) / 2; int y = (source.getHeight() - size) / 2; Bitmap squaredBitmap = Bitmap.createBitmap(source, x, y, size, size); if (squaredBitmap != source) { source.recycle(); } Bitmap bitmap = Bitmap.createBitmap(size, size, source.getConfig()); Canvas canvas = new Canvas(bitmap); Paint paint = new Paint(); BitmapShader shader = new BitmapShader(squaredBitmap, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP); float mScale = (mRadius * 2.0f) / Math.min(bitmap.getHeight(), bitmap.getWidth()); Matrix matrix = new Matrix(); matrix.setScale(mScale, mScale); bitmapShader.setLocalMatrix(matrix); paint.setShader(shader); paint.setAntiAlias(true); float r = size / 2f; canvas.drawCircle(r, r, r, paint); squaredBitmap.recycle(); return bitmap; }
5、修改畫素
該方法支援抗鋸齒,用法簡單,記憶體佔有率同樣處於中等水平。
public class CircleImageView extends AppCompatImageView {
public CircleImageView(Context context) {
this(context,null);
}
public CircleImageView(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public CircleImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public void onDraw(Canvas canvas) {
int width = getWidth();
int height = getHeight();
int minSize = Math.min(width,height)/2;
Drawable drawable = getDrawable();
if(drawable!=null && minSize!=0) {
if(Math.min(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight())==0) {
super.onDraw(canvas);
return;
}
int intrinsicWidth = drawable.getIntrinsicWidth();
int intrinsicHeight = drawable.getIntrinsicHeight();
float R = Math.min(intrinsicWidth,intrinsicHeight)/2;
Bitmap bmp = Bitmap.createBitmap(intrinsicWidth, intrinsicHeight, Bitmap.Config.ARGB_8888);
Canvas targetCanvas = new Canvas(bmp);
drawable.draw(targetCanvas);
for (int y=0;y<intrinsicHeight;y++){
for (int x=0;x<intrinsicWidth;x++){
if((Math.pow(x-intrinsicWidth/2,2) + Math.pow(y-intrinsicHeight/2,2))<=Math.pow(R,2)){
continue;
}
bmp.setPixel(x,y, Color.TRANSPARENT);
}
}
Matrix imageMatrix = getImageMatrix();
if(imageMatrix!=null){
canvas.concat(imageMatrix);
}
final int saveCount = canvas.getSaveCount();
canvas.save();
if (getCropToPadding()) {
final int scrollX = getScrollX();
final int scrollY = getScrollY();
canvas.clipRect(scrollX + getPaddingLeft(), scrollY + getPaddingTop(),
scrollX + getRight() - getLeft() - getPaddingRight(),
scrollY + getBottom() - getTop() - getPaddingBottom());
}
canvas.translate(getPaddingLeft(),getPaddingTop());
DrawFilter drawFilter = canvas.getDrawFilter();
canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG));
canvas.drawBitmap(bmp,0,0,null);
canvas.setDrawFilter(drawFilter);
canvas.restoreToCount(saveCount);
bmp.recycle();
}else{
super.onDraw(canvas);
}
}
}