本文共 13039 字，大约阅读时间需要 43 分钟。

用到了第三方插件，

NiceImageView

感兴趣可以去git搜一下。。

源码如下

package com.anguomob.love.view;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.RectF;import android.graphics.Xfermode;import android.os.Build;import android.util.AttributeSet;import android.util.TypedValue;import androidx.annotation.ColorInt;import androidx.annotation.Nullable;import androidx.appcompat.widget.AppCompatImageView;import com.anguomob.love.R;public class NiceImageView extends AppCompatImageView {    private Context context;    private boolean isCircle; // 是否显示为圆形，如果为圆形则设置的corner无效    private boolean isCoverSrc; // border、inner_border是否覆盖图片    private int borderWidth; // 边框宽度    private int borderColor = Color.WHITE; // 边框颜色    private int innerBorderWidth; // 内层边框宽度    private int innerBorderColor = Color.WHITE; // 内层边框充色    private int cornerRadius; // 统一设置圆角半径，优先级高于单独设置每个角的半径    private int cornerTopLeftRadius; // 左上角圆角半径    private int cornerTopRightRadius; // 右上角圆角半径    private int cornerBottomLeftRadius; // 左下角圆角半径    private int cornerBottomRightRadius; // 右下角圆角半径    private int maskColor; // 遮罩颜色    private Xfermode xfermode;    private int width;    private int height;    private float radius;    private float[] borderRadii;    private float[] srcRadii;    private RectF srcRectF; // 图片占的矩形区域    private RectF borderRectF; // 边框的矩形区域    private Paint paint;    private Path path; // 用来裁剪图片的ptah    private Path srcPath; // 图片区域大小的path    public NiceImageView(Context context) {        this(context, null);    }    public NiceImageView(Context context, @Nullable AttributeSet attrs) {        this(context, attrs, 0);    }    public NiceImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        this.context = context;        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.NiceImageView, 0, 0);        for (int i = 0; i < ta.getIndexCount(); i++) {            int attr = ta.getIndex(i);            if (attr == R.styleable.NiceImageView_niv_is_cover_src) {                isCoverSrc = ta.getBoolean(attr, isCoverSrc);            } else if (attr == R.styleable.NiceImageView_niv_is_circle) {                isCircle = ta.getBoolean(attr, isCircle);            } else if (attr == R.styleable.NiceImageView_niv_border_width) {                borderWidth = ta.getDimensionPixelSize(attr, borderWidth);            } else if (attr == R.styleable.NiceImageView_niv_border_color) {                borderColor = ta.getColor(attr, borderColor);            } else if (attr == R.styleable.NiceImageView_niv_inner_border_width) {                innerBorderWidth = ta.getDimensionPixelSize(attr, innerBorderWidth);            } else if (attr == R.styleable.NiceImageView_niv_inner_border_color) {                innerBorderColor = ta.getColor(attr, innerBorderColor);            } else if (attr == R.styleable.NiceImageView_niv_corner_radius) {                cornerRadius = ta.getDimensionPixelSize(attr, cornerRadius);            } else if (attr == R.styleable.NiceImageView_niv_corner_top_left_radius) {                cornerTopLeftRadius = ta.getDimensionPixelSize(attr, cornerTopLeftRadius);            } else if (attr == R.styleable.NiceImageView_niv_corner_top_right_radius) {                cornerTopRightRadius = ta.getDimensionPixelSize(attr, cornerTopRightRadius);            } else if (attr == R.styleable.NiceImageView_niv_corner_bottom_left_radius) {                cornerBottomLeftRadius = ta.getDimensionPixelSize(attr, cornerBottomLeftRadius);            } else if (attr == R.styleable.NiceImageView_niv_corner_bottom_right_radius) {                cornerBottomRightRadius = ta.getDimensionPixelSize(attr, cornerBottomRightRadius);            } else if (attr == R.styleable.NiceImageView_niv_mask_color) {                maskColor = ta.getColor(attr, maskColor);            }        }        ta.recycle();        borderRadii = new float[8];        srcRadii = new float[8];        borderRectF = new RectF();        srcRectF = new RectF();        paint = new Paint();        path = new Path();        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.O_MR1) {            xfermode = new PorterDuffXfermode(PorterDuff.Mode.DST_IN);        } else {            xfermode = new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);            srcPath = new Path();        }        calculateRadii();        clearInnerBorderWidth();    }    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        width = w;        height = h;        initBorderRectF();        initSrcRectF();    }    @Override    protected void onDraw(Canvas canvas) {        // 使用图形混合模式来显示指定区域的图片        canvas.saveLayer(srcRectF, null, Canvas.ALL_SAVE_FLAG);        if (!isCoverSrc) {            float sx = 1.0f * (width - 2 * borderWidth - 2 * innerBorderWidth) / width;            float sy = 1.0f * (height - 2 * borderWidth - 2 * innerBorderWidth) / height;            // 缩小画布，使图片内容不被borders覆盖            canvas.scale(sx, sy, width / 2.0f, height / 2.0f);        }        super.onDraw(canvas);        paint.reset();        path.reset();        if (isCircle) {            path.addCircle(width / 2.0f, height / 2.0f, radius, Path.Direction.CCW);        } else {            path.addRoundRect(srcRectF, srcRadii, Path.Direction.CCW);        }        paint.setAntiAlias(true);        paint.setStyle(Paint.Style.FILL);        paint.setXfermode(xfermode);        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.O_MR1) {            canvas.drawPath(path, paint);        } else {            srcPath.reset();            srcPath.addRect(srcRectF, Path.Direction.CCW);            // 计算tempPath和path的差集            srcPath.op(path, Path.Op.DIFFERENCE);            canvas.drawPath(srcPath, paint);        }        paint.setXfermode(null);        // 绘制遮罩        if (maskColor != 0) {            paint.setColor(maskColor);            canvas.drawPath(path, paint);        }        // 恢复画布        canvas.restore();        // 绘制边框        drawBorders(canvas);    }    private void drawBorders(Canvas canvas) {        if (isCircle) {            if (borderWidth > 0) {                drawCircleBorder(canvas, borderWidth, borderColor, radius - borderWidth / 2.0f);            }            if (innerBorderWidth > 0) {                drawCircleBorder(canvas, innerBorderWidth, innerBorderColor,                        radius - borderWidth - innerBorderWidth / 2.0f);            }        } else {            if (borderWidth > 0) {                drawRectFBorder(canvas, borderWidth, borderColor, borderRectF, borderRadii);            }        }    }    private void drawCircleBorder(Canvas canvas, int borderWidth, int borderColor, float radius) {        initBorderPaint(borderWidth, borderColor);        path.addCircle(width / 2.0f, height / 2.0f, radius, Path.Direction.CCW);        canvas.drawPath(path, paint);    }    private void drawRectFBorder(Canvas canvas, int borderWidth, int borderColor, RectF rectF,                                 float[] radii) {        initBorderPaint(borderWidth, borderColor);        path.addRoundRect(rectF, radii, Path.Direction.CCW);        canvas.drawPath(path, paint);    }    private void initBorderPaint(int borderWidth, int borderColor) {        path.reset();        paint.setStrokeWidth(borderWidth);        paint.setColor(borderColor);        paint.setStyle(Paint.Style.STROKE);    }    /**     * 计算外边框的RectF     */    private void initBorderRectF() {        if (!isCircle) {            borderRectF.set(borderWidth / 2.0f, borderWidth / 2.0f, width - borderWidth / 2.0f,                    height - borderWidth / 2.0f);        }    }    /**     * 计算图片原始区域的RectF     */    private void initSrcRectF() {        if (isCircle) {            radius = Math.min(width, height) / 2.0f;            srcRectF.set(width / 2.0f - radius, height / 2.0f - radius, width / 2.0f + radius,                    height / 2.0f + radius);        } else {            srcRectF.set(0, 0, width, height);            if (isCoverSrc) {                srcRectF = borderRectF;            }        }    }    /**     * 计算RectF的圆角半径     */    private void calculateRadii() {        if (isCircle) {            return;        }        if (cornerRadius > 0) {            for (int i = 0; i < borderRadii.length; i++) {                borderRadii[i] = cornerRadius;                srcRadii[i] = cornerRadius - borderWidth / 2.0f;            }        } else {            borderRadii[0] = borderRadii[1] = cornerTopLeftRadius;            borderRadii[2] = borderRadii[3] = cornerTopRightRadius;            borderRadii[4] = borderRadii[5] = cornerBottomRightRadius;            borderRadii[6] = borderRadii[7] = cornerBottomLeftRadius;            srcRadii[0] = srcRadii[1] = cornerTopLeftRadius - borderWidth / 2.0f;            srcRadii[2] = srcRadii[3] = cornerTopRightRadius - borderWidth / 2.0f;            srcRadii[4] = srcRadii[5] = cornerBottomRightRadius - borderWidth / 2.0f;            srcRadii[6] = srcRadii[7] = cornerBottomLeftRadius - borderWidth / 2.0f;        }    }    private void calculateRadiiAndRectF(boolean reset) {        if (reset) {            cornerRadius = 0;        }        calculateRadii();        initBorderRectF();        invalidate();    }    /**     * 目前圆角矩形情况下不支持inner_border，需要将其置0     */    private void clearInnerBorderWidth() {        if (!isCircle) {            this.innerBorderWidth = 0;        }    }    public void isCoverSrc(boolean isCoverSrc) {        this.isCoverSrc = isCoverSrc;        initSrcRectF();        invalidate();    }    public void isCircle(boolean isCircle) {        this.isCircle = isCircle;        clearInnerBorderWidth();        initSrcRectF();        invalidate();    }    public void setBorderWidth(int borderWidth) {        this.borderWidth = dp2px(borderWidth);        calculateRadiiAndRectF(false);    }    public void setBorderColor(@ColorInt int borderColor) {        this.borderColor = borderColor;        invalidate();    }    public void setInnerBorderWidth(int innerBorderWidth) {        this.innerBorderWidth = dp2px(innerBorderWidth);        clearInnerBorderWidth();        invalidate();    }    public void setInnerBorderColor(@ColorInt int innerBorderColor) {        this.innerBorderColor = innerBorderColor;        invalidate();    }    public void setCornerRadius(int cornerRadius) {        this.cornerRadius = dp2px(cornerRadius);        calculateRadiiAndRectF(false);    }    public void setCornerTopLeftRadius(int cornerTopLeftRadius) {        this.cornerTopLeftRadius = dp2px(cornerTopLeftRadius);        calculateRadiiAndRectF(true);    }    public void setCornerTopRightRadius(int cornerTopRightRadius) {        this.cornerTopRightRadius = dp2px(cornerTopRightRadius);        calculateRadiiAndRectF(true);    }    public void setCornerBottomLeftRadius(int cornerBottomLeftRadius) {        this.cornerBottomLeftRadius = dp2px(cornerBottomLeftRadius);        calculateRadiiAndRectF(true);    }    public void setCornerBottomRightRadius(int cornerBottomRightRadius) {        this.cornerBottomRightRadius = dp2px(cornerBottomRightRadius);        calculateRadiiAndRectF(true);    }    public void setMaskColor(@ColorInt int maskColor) {        this.maskColor = maskColor;        invalidate();    }    private int dp2px(int dp) {        return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,                context.getResources().getDisplayMetrics()));    }}

自定义样式

<?xml version="1.0" encoding="utf-8"?><resources>    <declare-styleable name="NiceImageView">        <attr name="niv_is_circle" format="boolean" />        <attr name="niv_is_cover_src" format="boolean" />        <attr name="niv_corner_radius" format="dimension" />        <attr name="niv_corner_top_left_radius" format="dimension" />        <attr name="niv_corner_top_right_radius" format="dimension" />        <attr name="niv_corner_bottom_left_radius" format="dimension" />        <attr name="niv_corner_bottom_right_radius" format="dimension" />        <attr name="niv_border_width" format="dimension" />        <attr name="niv_border_color" format="color" />        <attr name="niv_inner_border_width" format="dimension" />        <attr name="niv_inner_border_color" format="color" />        <attr name="niv_mask_color" format="color" />    </declare-styleable></resources>

使用也很简单

           <com.anguomob.love.view.NiceImageView                        android:id="@+id/mIvUpload"                        android:layout_width="40dp"                        android:layout_height="40dp"                        android:src="@mipmap/ic_launcher"                        android:textColor="@color/color_999999"                        android:textSize="18sp"                        android:visibility="gone"                        app:niv_is_circle="true" />