CircleImageView解析
首先、它是继承自ImageView，给ImageView设置图片的方法就是setImageXXX，不管你是用JAVA代码设置，还是在XML里面用src，它最终还是调用JAVA的setImageXXX方法，在这些个方法的最后一定有一个invalidate的方法，让其调用onDraw。
CircleImageView的原理也是这样，声明一个mBitmap这个就是要带到CircleImageView 里面的Bitmap，它的赋值都是在setImageXXX里面做的：
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
mBitmap = bm;
System.out.println("setImageBitmap -- setup");
setup();
}
@Override
public void setImageDrawable(Drawable drawable) {
super.setImageDrawable(drawable);
mBitmap = getBitmapFromDrawable(drawable);
System.out.println("setImageDrawable -- setup");
setup();
}
@Override
public void setImageResource(int resId) {
super.setImageResource(resId);
mBitmap = getBitmapFromDrawable(getDrawable());
System.out.println("setImageResource -- setup");
setup();
}
@Override
public void setImageURI(Uri uri) {
super.setImageURI(uri);
mBitmap = getBitmapFromDrawable(getDrawable());
System.out.println("setImageURI -- setup");
setup();
}
它们在设置完图片之后必定会调用setup方法，其实这个方法就是一个初始化操作而已，但是在setup的结束地方也调用了invalidate
它巧妙的用这个mBitmap为空，如果这个View还没有被设置图片则不会执行下面的方法 ，在setup里面有
private void setup() {
if (!mReady) {
mSetupPending = true;
return;
}
//这个mBitmap比较妙，只有当有图片被设置以后才会开始执行下面的方法。
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();
//整个图像的显示区域：即全部的View大小区域。
mBorderRect.set(0, 0, getWidth(), getHeight());
//Border的半径为长宽中取小的那一边，android中drawCircle的半径是内圆的半径，不是外圆的半径。
mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);
//图片显示的区域：即View的大小区域减去边界的大小。
mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);
//图片的半径大小取图片小边。
mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);
updateShaderMatrix();
invalidate();
}
这个方法应当是在onMeasure之后调用的，我们知道图片设置成功之后，一定是在onMeasure之后，
所以它并没有逃脱自定义控件的的逻辑（1、重写onMeasure计算或者设置一些高度、宽度等数据，2、重写onDraw 3、重写onTouch做一些事件处理或者计算），它只是通过一个mBitmap的防空来判断它是在绘制成功之后的做的事情。
再看看onDraw就更加明白了。
这个onDraw也是利用如果图片不存在就不画它，这是一个十分巧妙的判断。
@Override
protected void onDraw(Canvas canvas) {
System.out.println("onDraw before setup");
if (getDrawable() == null) {
return;
}
System.out.println("onDraw after setup");
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);
if (mBorderWidth != 0) {
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);
}
/**********图片延迟加载时间的各个方法的生命周期(模仿网络图片的加载情况)*****************/
//onSizeChanged --> onDraw --> setImageResource --> onDraw
}
整体来看思路是这样，这个View显示到页面时，如果没有图片资源其实是一个空画，就是虽然执行了onDraw但是并没有执行实际内容，只有当执行了setImageXXX，这里面是真正有内容了才去onDraw。
BitmapShader：使用一张位图作为纹理对某一区域进行填充，例如我们drawCircle，它就会对这个circle里面进行填充,它的两个参数就是对X，Y轴进行填充的一些规则。
package de.hdodenhof.circleimageview;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.util.AttributeSet;
import android.widget.ImageView;
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 = 2;
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) {
System.out.println("init -- setup");
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
public void setAdjustViewBounds(boolean adjustViewBounds) {
if (adjustViewBounds) {
throw new IllegalArgumentException("adjustViewBounds not supported.");
}
}
@Override
protected void onDraw(Canvas canvas) {
System.out.println("onDraw before setup");
if (getDrawable() == null) {
return;
}
System.out.println("onDraw after setup");
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);
if (mBorderWidth != 0) {
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);
}
/**********图片延迟加载时间的各个方法的生命周期(模仿网络图片的加载情况)*****************/
//onSizeChanged --> onDraw --> setImageResource --> onDraw
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
System.out.println("onSizeChanged -- setup");
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;
System.out.println("setBorderWidth -- setup");
setup();
}
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
mBitmap = bm;
System.out.println("setImageBitmap -- setup");
setup();
}
@Override
public void setImageDrawable(Drawable drawable) {
super.setImageDrawable(drawable);
mBitmap = getBitmapFromDrawable(drawable);
System.out.println("setImageDrawable -- setup");
setup();
}
@Override
public void setImageResource(int resId) {
super.setImageResource(resId);
mBitmap = getBitmapFromDrawable(getDrawable());
System.out.println("setImageResource -- setup");
setup();
}
@Override
public void setImageURI(Uri uri) {
super.setImageURI(uri);
mBitmap = getBitmapFromDrawable(getDrawable());
System.out.println("setImageURI -- setup");
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;
}
//这个mBitmap比较妙，只有当有图片被设置以后才会开始执行下面的方法。
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();
//整个图像的显示区域：即全部的View大小区域。
mBorderRect.set(0, 0, getWidth(), getHeight());
//Border的半径为长宽中取小的那一边，android中drawCircle的半径是内圆的半径，不是外圆的半径。
mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);
//图片显示的区域：即View的大小区域减去边界的大小。
mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);
//图片的半径大小取图片小边。
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;
}
System.out.println("scale "+scale);
mShaderMatrix.setScale(scale, scale);
mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth);
mBitmapShader.setLocalMatrix(mShaderMatrix);
}
}