android 自定义圆形imageView

头叙：

有的时候，android原生的控件满足不了我们项目中的需求，所以我们会针对原生的控件在进行一次升华，

也就是我们说的自定义控件。

eg: 每一个项目中都有imageView,但是原生的imageView是一个矩形，但是我们爱头像上传的时候，有可能需要圆形的头像，

我们只能自定义控件，

1.自定义控件

1.1 如果我们要自定义ImageView, 首先继承ImageView(具体代码，在下面会赘述，简单说下步骤)

1.2 实现三个构造方法（我们也可以在自定义一些属性）

我们在第三个构造方法中：

TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);

mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_civ_border_width, DEFAULT_BORDER_WIDTH);
mBorderColor = a.getColor(R.styleable.CircleImageView_civ_border_color, DEFAULT_BORDER_COLOR);

a.recycle();

实现我们自己定义的样式；（style）

<declare-styleable name="CircleImageView">
    <attr name="civ_border_width" format="dimension" />
    <attr name="civ_border_color" format="color" />
    <attr name="civ_border_overlay" format="boolean" />
    <attr name="civ_fill_color" format="color" />
</declare-styleable>

1.3 如果需要我们自己绘制：

需要重写三个重要的方法：（三个方法不一定全部重写，根据需求进行重写）

1 ）onMeause （测量）

2 )  onDraw （绘制）

3 )   onLayout  （布局）

1.4 我们在绘制的时候，需要笔和画布

笔的创建：（我们还可以对笔进行设置颜色，这里就不赘述了）

private final Paint mBitmapPaint = new Paint();

在画布上进行绘制：

Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);

2. 效果图展示：

3. 代码如下：

/**
 * 圆形
 */
public class CircleImageView extends android.support.v7.widget.AppCompatImageView {

    private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;

    private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;
    private static final int COLOR_DRAWABLE_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 ColorFilter mColorFilter;

    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_civ_border_width, DEFAULT_BORDER_WIDTH);
        mBorderColor = a.getColor(R.styleable.CircleImageView_civ_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
    public void setAdjustViewBounds(boolean adjustViewBounds) {
        if (adjustViewBounds) {
            throw new IllegalArgumentException("adjustViewBounds not supported.");
        }
    }

    @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();
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        if (cf == mColorFilter) {
            return;
        }

        mColorFilter = cf;
        mBitmapPaint.setColorFilter(mColorFilter);
        invalidate();
    }

    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(COLOR_DRAWABLE_DIMENSION, COLOR_DRAWABLE_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() / mBitmapHeight;
            dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
        } else {
            scale = mDrawableRect.width() / 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);
    }

}

5. 使用方法：

在xml布局中直接引用：

<com.juxin.textapp.view.CircleImageView
    android:id="@+id/img_view"
    android:layout_width="150dp"
    android:layout_height="150dp"
    android:src="@drawable/img"
    />

项目地址：

https://download.csdn.net/download/wk_beicai/10421969