前言:
目前网上有很多圆角图片的实例,Github上也有一些成熟的项目。之前做项目,为了稳定高效都是选用Github上的项目直接用。但这种结束也是Android开发必备技能 ,所以今天就来简单研究一下该技术,分享给大家。
预备知识:
Xfermode介绍:
下面是Android ApiDemo里的“Xfermodes”实例,效果图。
Xfermode有三个子类,结构如下:
public class Xfermode extends Object java.lang.Object ? android.graphics.Xfermode Known Direct Subclasses AvoidXfermode, PixelXorXfermode, PorterDuffXfermode
AvoidXfermode 指定了一个颜色和容差,强制Paint避免在它上面绘图(或者只在它上面绘图)。
PixelXorXfermode 当覆盖已有的颜色时,应用一个简单的像素异或操作。
PorterDuffXfermode 这是一个非常强大的转换模式,使用它,可以使用图像合成的16条Porter-Duff规则的任意一条来控制Paint如何与已有的Canvas图像进行交互。
上面图片种显示的16种模式介绍如下:
1.PorterDuff.Mode.CLEAR
所绘制不会提交到画布上。
2.PorterDuff.Mode.SRC
显示上层绘制图片
3.PorterDuff.Mode.DST
显示下层绘制图片
4.PorterDuff.Mode.SRC_OVER
正常绘制显示,上下层绘制叠盖。
5.PorterDuff.Mode.DST_OVER
上下层都显示。下层居上显示。
6.PorterDuff.Mode.SRC_IN
取两层绘制交集。显示上层。
7.PorterDuff.Mode.DST_IN
取两层绘制交集。显示下层。
8.PorterDuff.Mode.SRC_OUT
取上层绘制非交集部分。
9.PorterDuff.Mode.DST_OUT
取下层绘制非交集部分。
10.PorterDuff.Mode.SRC_ATOP
取下层非交集部分与上层交集部分
11.PorterDuff.Mode.DST_ATOP
取上层非交集部分与下层交集部分
12.PorterDuff.Mode.XOR
异或:去除两图层交集部分
13.PorterDuff.Mode.DARKEN
取两图层全部区域,交集部分颜色加深
14.PorterDuff.Mode.LIGHTEN
取两图层全部,点亮交集部分颜色
15.PorterDuff.Mode.MULTIPLY
取两图层交集部分叠加后颜色
16.PorterDuff.Mode.SCREEN
取两图层全部区域,交集部分变为透明色
了解了上面的知识点后,我们根据上面的知识点先来实现第一种圆角图片制作方式:
原图:
先看这一段代码
private ImageView mImg; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mImg = (ImageView) findViewById(R.id.img); //获得imageview中设置的图片 BitmapDrawable drawable = (BitmapDrawable) mImg.getDrawable(); Bitmap bmp = drawable.getBitmap(); //获得图片的宽,并创建结果bitmap int width = bmp.getWidth(); Bitmap resultBmp = Bitmap.createBitmap(width, width, Bitmap.Config.ARGB_8888); Paint paint = new Paint(); Canvas canvas = new Canvas(resultBmp); //画圆 canvas.drawCircle(width / 2, width / 2, width / 2, paint); paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));// 选择交集去上层图片 canvas.drawBitmap(bmp, 0, 0, paint); mImg.setImageBitmap(resultBmp); bmp.recycle(); }
通过运行上面的代码,我们得出的结果如下:
大家看到这是我们需要的结果。可是这样做可能导致OutOfMomery异常。假如图片很大或者你可能并非通过ImageView的getDrawable获得图像,而是直接Decode一张很大的图片加载到内存,你会发现可能会出现异常。我们做一下改变。
private static final String TAG = "RoundImage"; private ImageView mImg; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mImg = (ImageView) findViewById(R.id.img); // 裁剪图片 BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory .decodeResource(getResources(), R.drawable.avatar, options); Log.d(TAG, "original outwidth: " + options.outWidth); // 此宽度是目标ImageView希望的大小,你可以自定义ImageView,然后获得ImageView的宽度。 int dstWidth = 150; // 我们需要加载的图片可能很大,我们先对原有的图片进行裁剪 int sampleSize = calculateInSampleSize(options, dstWidth, dstWidth); options.inSampleSize = sampleSize; options.inJustDecodeBounds = false; Log.d(TAG, "sample size: " + sampleSize); Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.avatar, options); // 绘制图片 Bitmap resultBmp = Bitmap.createBitmap(dstWidth, dstWidth, Bitmap.Config.ARGB_8888); Paint paint = new Paint(); paint.setAntiAlias(true); Canvas canvas = new Canvas(resultBmp); // 画圆 canvas.drawCircle(dstWidth / 2, dstWidth / 2, dstWidth / 2, paint); // 选择交集去上层图片 paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); canvas.drawBitmap(bmp, new Rect(0, 0, bmp.getWidth(), bmp.getWidth()), new Rect(0, 0, dstWidth, dstWidth), paint); mImg.setImageBitmap(resultBmp); bmp.recycle(); } private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) { // Raw height and width of image final int height = options.outHeight; final int width = options.outWidth; int inSampleSize = 1; if (height > reqHeight || width > reqWidth) { final int halfHeight = height / 2; final int halfWidth = width / 2; // Calculate the largest inSampleSize value that is a power of 2 and // keeps both // height and width larger than the requested height and width. while ((halfHeight / inSampleSize) > reqHeight && (halfWidth / inSampleSize) > reqWidth) { inSampleSize *= 2; } } return inSampleSize; }
再来看一下效果:
上面提供了一种方式,更多细节,需要你自己去优化,下面介绍第二种绘制圆角图片的方式。
首先我们需要了解一个类BitmapShader
引用的介绍如下:
public BitmapShader(Bitmap bitmap,Shader.TileMode tileX,Shader.TileMode tileY)
调用这个方法来产生一个画有一个位图的渲染器(Shader)。
bitmap 在渲染器内使用的位图
tileX The tiling mode for x to draw the bitmap in. 在位图上X方向花砖模式
tileY The tiling mode for y to draw the bitmap in. 在位图上Y方向花砖模式
TileMode:(一共有三种)
CLAMP :如果渲染器超出原始边界范围,会复制范围内边缘染色。
REPEAT :横向和纵向的重复渲染器图片,平铺。
MIRROR :横向和纵向的重复渲染器图片,这个和REPEAT 重复方式不一样,他是以镜像方式平铺。
知道这个原理后,我们贴出对应的代码:
public class CircleImageView extends ImageView { private static final String TAG = CircleImageView.class.getSimpleName(); private Paint mBitmapPaint = new Paint(); private int mRadius; public CircleImageView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } public CircleImageView(Context context, AttributeSet attrs) { super(context, attrs); init(); } public CircleImageView(Context context) { super(context); init(); } private void init() { BitmapDrawable drawable = (BitmapDrawable) getDrawable(); if (drawable == null) { Log.i(TAG, "drawable: null"); return; } Bitmap bmp = drawable.getBitmap(); BitmapShader shader = new BitmapShader(bmp, TileMode.CLAMP, TileMode.CLAMP); mBitmapPaint.setShader(shader); mBitmapPaint.setAntiAlias(true); invalidate(); } @Override protected void onDraw(Canvas canvas) { if (getDrawable() == null) { return; } mRadius = Math.min(getWidth()/2, getHeight()/2); canvas.drawCircle(getWidth() / 2, getHeight() / 2, mRadius, mBitmapPaint); } }
是不是挺简单的
结果我就不显示了,跟上面的一样。上面也是最原始的代码,文章的结尾贴出一份完整优化过的代码共大家参考如下:
public class CircleImageView extends ImageView { private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP; private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888; private static final int COLORDRAWABLE_DIMENSION = 1; private static final int DEFAULT_BORDER_WIDTH = 0; private static final int DEFAULT_BORDER_COLOR = Color.BLACK; private final RectF mDrawableRect = new RectF(); private final RectF mBorderRect = new RectF(); private final Matrix mShaderMatrix = new Matrix(); private final Paint mBitmapPaint = new Paint(); private final Paint mBorderPaint = new Paint(); private int mBorderColor = DEFAULT_BORDER_COLOR; private int mBorderWidth = DEFAULT_BORDER_WIDTH; private Bitmap mBitmap; private BitmapShader mBitmapShader; private int mBitmapWidth; private int mBitmapHeight; private float mDrawableRadius; private float mBorderRadius; private boolean mReady; private boolean mSetupPending; public CircleImageView(Context context) { super(context); init(); } public CircleImageView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CircleImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0); mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH); mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR); a.recycle(); init(); } private void init() { super.setScaleType(SCALE_TYPE); mReady = true; if (mSetupPending) { setup(); mSetupPending = false; } } @Override public ScaleType getScaleType() { return SCALE_TYPE; } @Override public void setScaleType(ScaleType scaleType) { if (scaleType != SCALE_TYPE) { throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType)); } } @Override protected void onDraw(Canvas canvas) { if (getDrawable() == null) { return; } canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint); if (mBorderWidth != 0) { canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint); } } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); setup(); } public int getBorderColor() { return mBorderColor; } public void setBorderColor(int borderColor) { if (borderColor == mBorderColor) { return; } mBorderColor = borderColor; mBorderPaint.setColor(mBorderColor); invalidate(); } public int getBorderWidth() { return mBorderWidth; } public void setBorderWidth(int borderWidth) { if (borderWidth == mBorderWidth) { return; } mBorderWidth = borderWidth; setup(); } @Override public void setImageBitmap(Bitmap bm) { super.setImageBitmap(bm); mBitmap = bm; setup(); } @Override public void setImageDrawable(Drawable drawable) { super.setImageDrawable(drawable); mBitmap = getBitmapFromDrawable(drawable); setup(); } @Override public void setImageResource(int resId) { super.setImageResource(resId); mBitmap = getBitmapFromDrawable(getDrawable()); setup(); } @Override public void setImageURI(Uri uri) { super.setImageURI(uri); mBitmap = getBitmapFromDrawable(getDrawable()); setup(); } private Bitmap getBitmapFromDrawable(Drawable drawable) { if (drawable == null) { return null; } if (drawable instanceof BitmapDrawable) { return ((BitmapDrawable) drawable).getBitmap(); } try { Bitmap bitmap; if (drawable instanceof ColorDrawable) { bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG); } else { bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG); } Canvas canvas = new Canvas(bitmap); drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight()); drawable.draw(canvas); return bitmap; } catch (OutOfMemoryError e) { return null; } } private void setup() { if (!mReady) { mSetupPending = true; return; } if (mBitmap == null) { return; } mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); mBitmapPaint.setAntiAlias(true); mBitmapPaint.setShader(mBitmapShader); mBorderPaint.setStyle(Paint.Style.STROKE); mBorderPaint.setAntiAlias(true); mBorderPaint.setColor(mBorderColor); mBorderPaint.setStrokeWidth(mBorderWidth); mBitmapHeight = mBitmap.getHeight(); mBitmapWidth = mBitmap.getWidth(); mBorderRect.set(0, 0, getWidth(), getHeight()); mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2); mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth); mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2); updateShaderMatrix(); invalidate(); } private void updateShaderMatrix() { float scale; float dx = 0; float dy = 0; mShaderMatrix.set(null); if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) { scale = mDrawableRect.height() / (float) mBitmapHeight; dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f; } else { scale = mDrawableRect.width() / (float) mBitmapWidth; dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f; } mShaderMatrix.setScale(scale, scale); mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth); mBitmapShader.setLocalMatrix(mShaderMatrix); } }
补充一点上面的都是圆形图片,圆角的如何制作呢?这个问题留给你思考吧。
全文完