java - 圆形 ImageView 拉伸(stretch)

Question

我正在使用以下代码在我的项目中创建圆形 ImageView 。

public class CircularImageView extends ImageView {
    // Border & Selector configuration variables
    private boolean hasBorder;
    private boolean hasSelector;
    private boolean isSelected;
    private int borderWidth;
    private int canvasSize;
    private int selectorStrokeWidth;

    // Objects used for the actual drawing
    private BitmapShader shader;
    private Bitmap image;
    private Paint paint;
    private Paint paintBorder;
    private Paint paintSelectorBorder;
    private ColorFilter selectorFilter;

    public CircularImageView(Context context) {
        this(context, null);
    }

    public CircularImageView(Context context, AttributeSet attrs)
    {
        this(context, attrs, R.attr.circularImageViewStyle);
    }

    public CircularImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs, defStyle);
    }

    /**
     * Initializes paint objects and sets desired attributes.
     *
     * @param context
     * @param attrs
     * @param defStyle
     */
    private void init(Context context, AttributeSet attrs, int defStyle) {
        // Initialize paint objects
        paint = new Paint();
        paint.setAntiAlias(true);
        paintBorder = new Paint();
        paintBorder.setAntiAlias(true);
        paintSelectorBorder = new Paint();
        paintSelectorBorder.setAntiAlias(true);

        // load the styled attributes and set their properties
        TypedArray attributes = context.obtainStyledAttributes(attrs, R.styleable.CircularImageView, defStyle, 0);

        // Check if border and/or border is enabled
        hasBorder = attributes.getBoolean(R.styleable.CircularImageView_border, false);
        hasSelector = attributes.getBoolean(R.styleable.CircularImageView_selector, false);

        // Set border properties if enabled
        if(hasBorder) {
            int defaultBorderSize = (int) (2 * context.getResources().getDisplayMetrics().density + 0.5f);
            setBorderWidth(attributes.getDimensionPixelOffset(R.styleable.CircularImageView_border_width, defaultBorderSize));
            setBorderColor(attributes.getColor(R.styleable.CircularImageView_border_color, Color.WHITE));
        }

        // Set selector properties if enabled
        if(hasSelector) {
            int defaultSelectorSize = (int) (2 * context.getResources().getDisplayMetrics().density + 0.5f);
            setSelectorColor(attributes.getColor(
                R.styleable.CircularImageView_selector_color, Color.TRANSPARENT));
            setSelectorStrokeWidth(attributes.getDimensionPixelOffset(R.styleable.CircularImageView_selector_stroke_width, defaultSelectorSize));
            setSelectorStrokeColor(attributes.getColor(R.styleable.CircularImageView_selector_stroke_color, Color.BLUE));
        }

        // Add shadow if enabled
        if(attributes.getBoolean(R.styleable.CircularImageView_shadow, false))
            addShadow();

        // We no longer need our attributes TypedArray, give it back to cache
        attributes.recycle();
    }

    /**
     * Sets the CircularImageView's border width in pixels.
     *
     * @param borderWidth
     */
    public void setBorderWidth(int borderWidth) {
        this.borderWidth = borderWidth;
        this.requestLayout();
        this.invalidate();
    }

    /**
     * Sets the CircularImageView's basic border color.
     *
     * @param borderColor
     */
    public void setBorderColor(int borderColor) {
        if (paintBorder != null)
            paintBorder.setColor(borderColor);
        this.invalidate();
    }

    /**
     * Sets the color of the selector to be draw over the
     * CircularImageView. Be sure to provide some opacity.
     *
     * @param selectorColor
     */
    public void setSelectorColor(int selectorColor) {
        this.selectorFilter = new PorterDuffColorFilter(selectorColor, PorterDuff.Mode.SRC_ATOP);
        this.invalidate();
    }

    /**
     * Sets the stroke width to be drawn around the CircularImageView
     * during click events when the selector is enabled.
     *
     * @param selectorStrokeWidth
     */
    public void setSelectorStrokeWidth(int selectorStrokeWidth) {
        this.selectorStrokeWidth = selectorStrokeWidth;
        this.requestLayout();
        this.invalidate();
    }

    /**
     * Sets the stroke color to be drawn around the CircularImageView
     * during click events when the selector is enabled.
     *
     * @param selectorStrokeColor
     */
    public void setSelectorStrokeColor(int selectorStrokeColor) {
        if (paintSelectorBorder != null)
            paintSelectorBorder.setColor(selectorStrokeColor);
        this.invalidate();
    }

    /**
     * Adds a dark shadow to this CircularImageView.
     */
    public void addShadow() {
        setLayerType(LAYER_TYPE_SOFTWARE, paintBorder);
        paintBorder.setShadowLayer(4.0f, 0.0f, 2.0f, Color.BLACK);
    }


    @Override
    public void onDraw(Canvas canvas) {
        // Don't draw anything without an image
        if(image == null)
            return;

        // Nothing to draw (Empty bounds)
        if(image.getHeight() == 0 || image.getWidth() == 0)
            return;

        // Compare canvas sizes
        int oldCanvasSize = canvasSize;

        canvasSize = canvas.getWidth();
        if(canvas.getHeight() < canvasSize)
            canvasSize = canvas.getHeight();

        // Reinitialize shader, if necessary
        if(oldCanvasSize != canvasSize)
            refreshBitmapShader();

        // Apply shader to paint
        paint.setShader(shader);

        // Keep track of selectorStroke/border width
        int outerWidth = 0;

        // Get the exact X/Y axis of the view
        int center = canvasSize / 2;


        if(hasSelector && isSelected) { // Draw the selector stroke & apply the selector filter, if applicable
            outerWidth = selectorStrokeWidth;
            center = (canvasSize - (outerWidth * 2)) / 2;

            paint.setColorFilter(selectorFilter);
            canvas.drawCircle(center + outerWidth, center + outerWidth, ((canvasSize - (outerWidth * 2)) / 2) + outerWidth - 4.0f, paintSelectorBorder);
        }
        else if(hasBorder) { // If no selector was drawn, draw a border and clear the filter instead... if enabled
            outerWidth = borderWidth;
            center = (canvasSize - (outerWidth * 2)) / 2;

            paint.setColorFilter(null);
            canvas.drawCircle(center + outerWidth, center + outerWidth, ((canvasSize - (outerWidth * 2)) / 2) + outerWidth - 4.0f, paintBorder);
        }
        else // Clear the color filter if no selector nor border were drawn
            paint.setColorFilter(null);

        // Draw the circular image itself
        canvas.drawCircle(center + outerWidth, center + outerWidth, ((canvasSize - (outerWidth * 2)) / 2) - 4.0f, paint);
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        // Check for clickable state and do nothing if disabled
        if(!this.isClickable()) {
            this.isSelected = false;
            return super.onTouchEvent(event);
        }

        // Set selected state based on Motion Event
        switch(event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                this.isSelected = true;
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_SCROLL:
            case MotionEvent.ACTION_OUTSIDE:
            case MotionEvent.ACTION_CANCEL:
                this.isSelected = false;
                break;
        }

        // Redraw image and return super type
        this.invalidate();
        return super.dispatchTouchEvent(event);
    }

    public void invalidate(Rect dirty) {
        super.invalidate(dirty);
        image = drawableToBitmap(getDrawable());
        if(shader != null || canvasSize > 0)
            refreshBitmapShader();
    }

    public void invalidate(int l, int t, int r, int b) {
        super.invalidate(l, t, r, b);
        image = drawableToBitmap(getDrawable());
        if(shader != null || canvasSize > 0)
            refreshBitmapShader();
    }

    @Override
    public void invalidate() {
        super.invalidate();
        image = drawableToBitmap(getDrawable());
        if(shader != null || canvasSize > 0)
            refreshBitmapShader();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int width = measureWidth(widthMeasureSpec);
        int height = measureHeight(heightMeasureSpec);
        setMeasuredDimension(width, height);
    }

    private int measureWidth(int measureSpec) {
        int result;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            // The parent has determined an exact size for the child.
            result = specSize;
        }
        else if (specMode == MeasureSpec.AT_MOST) {
            // The child can be as large as it wants up to the specified size.
            result = specSize;
        }
        else {
            // The parent has not imposed any constraint on the child.
            result = canvasSize;
        }

        return result;
    }

    private int measureHeight(int measureSpecHeight) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpecHeight);
        int specSize = MeasureSpec.getSize(measureSpecHeight);

        if (specMode == MeasureSpec.EXACTLY) {
            // We were told how big to be
            result = specSize;
        } else if (specMode == MeasureSpec.AT_MOST) {
            // The child can be as large as it wants up to the specified size.
            result = specSize;
        } else {
            // Measure the text (beware: ascent is a negative number)
            result = canvasSize;
        }

        return (result + 2);
    }

    /**
     * Convert a drawable object into a Bitmap
     *
     * @param drawable
     * @return
     */
    public Bitmap drawableToBitmap(Drawable drawable) {
        if (drawable == null) { // Don't do anything without a proper drawable
            return null;
        }
        else if (drawable instanceof BitmapDrawable) { // Use the getBitmap() method instead if BitmapDrawable
            return ((BitmapDrawable) drawable).getBitmap();
        }

        // Create Bitmap object out of the drawable
        Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),
                drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        drawable.draw(canvas);

        return bitmap;
    }

    /**
     * Reinitializes the shader texture used to fill in
     * the Circle upon drawing.
     */
    public void refreshBitmapShader() {
        shader = new BitmapShader(Bitmap.createScaledBitmap(image, canvasSize, canvasSize, false), Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
    }

    /**
     * Returns whether or not this view is currently
     * in its selected state.
     */
    public boolean isSelected() {
        return this.isSelected;
    }
}

圆形效果已创建，但问题是我的所有图片都变窄了，因为图片太大并且试图适应圆形 ImageView 。任何可能的解决方案？谢谢!

Answer 1

假设圆形 ImageView 的大小是固定的，避免拉伸(stretch)图像的唯一方法是将其裁剪为与 ImageView 相同的纵横比，或者在顶部或侧面引入边距。

因为您已经在 refreshBitmapShader() 中将位图缩放到 Canvas 大小，所以这是使用 Bitmap.createBitmap() 裁剪它的方便位置:

public void refreshBitmapShader() {        
    int left = 0; y = 0; w = image.getWidth(), h = image.getHeight(); 
    // decide whether we have to crop the sizes or the top and bottom:
    if(w > h)  // width is greater than height
    {
        x = (w - h) >> 1;   // crop sides, half on each side
        w = h;
    }
    else
    {
        y = (h - w) >> 1;   // crop top and bottom
        h = w;
    }
    Matrix m = new Matrix();
    float scale = (float)canvasSize / (float)w;
    m.preScale(scale, scale);   // scale to canvas size
    shader = new BitmapShader(Bitmap.createBitmap(image, x, y, w, h, m, false), Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
}