349 lines
13 KiB
Plaintext
349 lines
13 KiB
Plaintext
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package com.novelbook.android.view;
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import android.content.Context;
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import android.content.res.TypedArray;
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import android.graphics.Bitmap;
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import android.graphics.BitmapShader;
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import android.graphics.Canvas;
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import android.graphics.Color;
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import android.graphics.ColorFilter;
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import android.graphics.Matrix;
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import android.graphics.Paint;
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import android.graphics.RectF;
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import android.graphics.Shader;
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import android.graphics.drawable.BitmapDrawable;
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import android.graphics.drawable.ColorDrawable;
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import android.graphics.drawable.Drawable;
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import android.net.Uri;
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import android.support.annotation.ColorRes;
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import android.support.annotation.DrawableRes;
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import android.util.AttributeSet;
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import android.widget.ImageView;
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import com.novelbook.android.R;
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/**
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* 流程控制的比较严谨，比如setup函数的使用
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* updateShaderMatrix保证图片损失度最小和始终绘制图片正中央的那部分
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* 作者思路是画圆用渲染器位图填充，而不是把Bitmap重绘切割成一个圆形图片。
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*/
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public class CircleImageView extends ImageView {
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//缩放类型
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private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;
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private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;
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private static final int COLORDRAWABLE_DIMENSION = 2;
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// 默认边界宽度
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private static final int DEFAULT_BORDER_WIDTH = 0;
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// 默认边界颜色
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private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
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private static final boolean DEFAULT_BORDER_OVERLAY = false;
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private final RectF mDrawableRect = new RectF();
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private final RectF mBorderRect = new RectF();
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private final Matrix mShaderMatrix = new Matrix();
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//这个画笔最重要的是关联了mBitmapShader 使canvas在执行的时候可以切割原图片(mBitmapShader是关联了原图的bitmap的)
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private final Paint mBitmapPaint = new Paint();
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//这个描边，则与本身的原图bitmap没有任何关联，
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private final Paint mBorderPaint = new Paint();
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//这里定义了 圆形边缘的默认宽度和颜色
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private int mBorderColor = DEFAULT_BORDER_COLOR;
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private int mBorderWidth = DEFAULT_BORDER_WIDTH;
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private Bitmap mBitmap;
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private BitmapShader mBitmapShader; // 位图渲染
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private int mBitmapWidth; // 位图宽度
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private int mBitmapHeight; // 位图高度
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private float mDrawableRadius;// 图片半径
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private float mBorderRadius;// 带边框的的图片半径
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private ColorFilter mColorFilter;
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//初始false
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private boolean mReady;
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private boolean mSetupPending;
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private boolean mBorderOverlay;
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//构造函数
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public CircleImageView(Context context) {
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super(context);
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init();
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}
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//构造函数
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public CircleImageView(Context context, AttributeSet attrs) {
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this(context, attrs, 0);
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}
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/**
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* 构造函数
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*/
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public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
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super(context, attrs, defStyle);
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//通过obtainStyledAttributes 获得一组值赋给 TypedArray（数组） , 这一组值来自于res/values/attrs.xml中的name="CircleImageView"的declare-styleable中。
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TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);
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//通过TypedArray提供的一系列方法getXXXX取得我们在xml里定义的参数值；
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// 获取边界的宽度
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mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);
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// 获取边界的颜色
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mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR);
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mBorderOverlay = DEFAULT_BORDER_OVERLAY;
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//调用 recycle() 回收TypedArray,以便后面重用
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a.recycle();
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System.out.println("CircleImageView -- 构造函数");
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init();
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}
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/**
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* 作用就是保证第一次执行setup函数里下面代码要在构造函数执行完毕时调用
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*/
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private void init() {
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//在这里ScaleType被强制设定为CENTER_CROP，就是将图片水平垂直居中，进行缩放。
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super.setScaleType(SCALE_TYPE);
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mReady = true;
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if (mSetupPending) {
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setup();
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mSetupPending = false;
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}
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}
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@Override
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public ScaleType getScaleType() {
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return SCALE_TYPE;
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}
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/**
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* 这里明确指出 此种imageview 只支持CENTER_CROP 这一种属性
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*
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* @param scaleType
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*/
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@Override
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public void setScaleType(ScaleType scaleType) {
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if (scaleType != SCALE_TYPE) {
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throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType));
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}
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}
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@Override
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public void setAdjustViewBounds(boolean adjustViewBounds) {
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if (adjustViewBounds) {
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throw new IllegalArgumentException("adjustViewBounds not supported.");
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}
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}
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@Override
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protected void onDraw(Canvas canvas) {
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//如果图片不存在就不画
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if (getDrawable() == null) {
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return;
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}
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//绘制内圆形 图片 画笔为mBitmapPaint
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canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);
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//如果圆形边缘的宽度不为0 我们还要绘制带边界的外圆形 边界画笔为mBorderPaint
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if (mBorderWidth != 0) {
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canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);
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}
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}
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@Override
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protected void onSizeChanged(int w, int h, int oldw, int oldh) {
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super.onSizeChanged(w, h, oldw, oldh);
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setup();
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}
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public int getBorderColor() {
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return mBorderColor;
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}
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public void setBorderColor(int borderColor) {
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if (borderColor == mBorderColor) {
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return;
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}
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mBorderColor = borderColor;
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mBorderPaint.setColor(mBorderColor);
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invalidate();
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}
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public void setBorderColorResource(@ColorRes int borderColorRes) {
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setBorderColor(getContext().getResources().getColor(borderColorRes));
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}
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public int getBorderWidth() {
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return mBorderWidth;
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}
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public void setBorderWidth(int borderWidth) {
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if (borderWidth == mBorderWidth) {
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return;
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}
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mBorderWidth = borderWidth;
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setup();
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}
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public boolean isBorderOverlay() {
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return mBorderOverlay;
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}
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public void setBorderOverlay(boolean borderOverlay) {
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if (borderOverlay == mBorderOverlay) {
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return;
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}
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mBorderOverlay = borderOverlay;
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setup();
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}
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/**
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* 以下四个函数都是
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* 复写ImageView的setImageXxx()方法
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* 注意这个函数先于构造函数调用之前调用
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* @param bm
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*/
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@Override
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public void setImageBitmap(Bitmap bm) {
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super.setImageBitmap(bm);
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mBitmap = bm;
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setup();
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}
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@Override
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public void setImageDrawable(Drawable drawable) {
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super.setImageDrawable(drawable);
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mBitmap = getBitmapFromDrawable(drawable);
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System.out.println("setImageDrawable -- setup");
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setup();
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}
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@Override
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public void setImageResource(@DrawableRes int resId) {
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super.setImageResource(resId);
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mBitmap = getBitmapFromDrawable(getDrawable());
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setup();
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}
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@Override
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public void setImageURI(Uri uri) {
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super.setImageURI(uri);
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mBitmap = getBitmapFromDrawable(getDrawable());
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setup();
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}
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@Override
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public void setColorFilter(ColorFilter cf) {
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if (cf == mColorFilter) {
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return;
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}
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mColorFilter = cf;
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mBitmapPaint.setColorFilter(mColorFilter);
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invalidate();
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}
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/**
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* Drawable转Bitmap
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* @param drawable
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* @return
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*/
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private Bitmap getBitmapFromDrawable(Drawable drawable) {
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if (drawable == null) {
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return null;
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}
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if (drawable instanceof BitmapDrawable) {
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//通常来说 我们的代码就是执行到这里就返回了。返回的就是我们最原始的bitmap
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return ((BitmapDrawable) drawable).getBitmap();
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}
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try {
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Bitmap bitmap;
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if (drawable instanceof ColorDrawable) {
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bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG);
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} else {
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bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG);
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}
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Canvas canvas = new Canvas(bitmap);
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drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
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drawable.draw(canvas);
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return bitmap;
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} catch (OutOfMemoryError e) {
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return null;
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}
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}
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/**
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* 这个函数很关键，进行图片画笔边界画笔(Paint)一些重绘参数初始化：
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* 构建渲染器BitmapShader用Bitmap来填充绘制区域,设置样式以及内外圆半径计算等，
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* 以及调用updateShaderMatrix()函数和 invalidate()函数；
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*/
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private void setup() {
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//因为mReady默认值为false,所以第一次进这个函数的时候if语句为真进入括号体内
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//设置mSetupPending为true然后直接返回，后面的代码并没有执行。
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if (!mReady) {
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mSetupPending = true;
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return;
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}
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//防止空指针异常
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if (mBitmap == null) {
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return;
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}
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// 构建渲染器，用mBitmap位图来填充绘制区域 ，参数值代表如果图片太小的话 就直接拉伸
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mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
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// 设置图片画笔反锯齿
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mBitmapPaint.setAntiAlias(true);
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// 设置图片画笔渲染器
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mBitmapPaint.setShader(mBitmapShader);
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// 设置边界画笔样式
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mBorderPaint.setStyle(Paint.Style.STROKE);//设画笔为空心
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mBorderPaint.setAntiAlias(true);
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mBorderPaint.setColor(mBorderColor); //画笔颜色
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mBorderPaint.setStrokeWidth(mBorderWidth);//画笔边界宽度
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//这个地方是取的原图片的宽高
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mBitmapHeight = mBitmap.getHeight();
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mBitmapWidth = mBitmap.getWidth();
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// 设置含边界显示区域，取的是CircleImageView的布局实际大小，为方形，查看xml也就是160dp(240px) getWidth得到是某个view的实际尺寸
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mBorderRect.set(0, 0, getWidth(), getHeight());
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//计算 圆形带边界部分（外圆）的最小半径，取mBorderRect的宽高减去一个边缘大小的一半的较小值（这个地方我比较纳闷为什么求外圆半径需要先减去一个边缘大小）
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mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);
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// 初始图片显示区域为mBorderRect（CircleImageView的布局实际大小）
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mDrawableRect.set(mBorderRect);
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if (!mBorderOverlay) {
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//demo里始终执行
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//通过inset方法 使得图片显示的区域从mBorderRect大小上下左右内移边界的宽度形成区域，查看xml边界宽度为2dp（3px）,所以方形边长为就是160-4=156dp(234px)
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mDrawableRect.inset(mBorderWidth, mBorderWidth);
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}
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//这里计算的是内圆的最小半径，也即去除边界宽度的半径
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mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);
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//设置渲染器的变换矩阵也即是mBitmap用何种缩放形式填充
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updateShaderMatrix();
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//手动触发ondraw()函数 完成最终的绘制
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invalidate();
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}
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/**
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* 这个函数为设置BitmapShader的Matrix参数，设置最小缩放比例，平移参数。
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* 作用：保证图片损失度最小和始终绘制图片正中央的那部分
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*/
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private void updateShaderMatrix() {
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float scale;
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float dx = 0;
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float dy = 0;
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|||
|
|
|
|||
|
|
mShaderMatrix.set(null);
|
|||
|
|
// 这里不好理解 这个不等式也就是(mBitmapWidth / mDrawableRect.width()) > (mBitmapHeight / mDrawableRect.height())
|
|||
|
|
//取最小的缩放比例
|
|||
|
|
if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) {
|
|||
|
|
//y轴缩放 x轴平移 使得图片的y轴方向的边的尺寸缩放到图片显示区域（mDrawableRect）一样）
|
|||
|
|
scale = mDrawableRect.height() / (float) mBitmapHeight;
|
|||
|
|
dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
|
|||
|
|
} else {
|
|||
|
|
//x轴缩放 y轴平移 使得图片的x轴方向的边的尺寸缩放到图片显示区域（mDrawableRect）一样）
|
|||
|
|
scale = mDrawableRect.width() / (float) mBitmapWidth;
|
|||
|
|
dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;
|
|||
|
|
}
|
|||
|
|
// shaeder的变换矩阵，我们这里主要用于放大或者缩小。
|
|||
|
|
mShaderMatrix.setScale(scale, scale);
|
|||
|
|
// 平移
|
|||
|
|
mShaderMatrix.postTranslate((int) (dx + 0.5f) + mDrawableRect.left, (int) (dy + 0.5f) + mDrawableRect.top);
|
|||
|
|
// 设置变换矩阵
|
|||
|
|
mBitmapShader.setLocalMatrix(mShaderMatrix);
|
|||
|
|
}
|
|||
|
|
}
|