abstractregionpainter.java

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         * @param insets The stretching insets. May be null. If null, then assumed to be 0, 0, 0, 0.
         * @param canvasSize The size of the canvas used when encoding the various x/y values. May be null.
         *                   If null, then it is assumed that there are no encoded values, and any calls
         *                   to one of the "decode" methods will return the passed in value.
         * @param inverted Whether to "invert" the meaning of the 9-square grid and stretching insets
         */
        public PaintContext(Insets insets, Dimension canvasSize, boolean inverted) {
            this(insets, canvasSize, inverted, null, 1, 1);
        }

        /**
         * Creates a new PaintContext.
         *
         * @param insets The stretching insets. May be null. If null, then assumed to be 0, 0, 0, 0.
         * @param canvasSize The size of the canvas used when encoding the various x/y values. May be null.
         *                   If null, then it is assumed that there are no encoded values, and any calls
         *                   to one of the "decode" methods will return the passed in value.
         * @param inverted Whether to "invert" the meaning of the 9-square grid and stretching insets
         * @param cacheMode A hint as to which caching mode to use. If null, then set to no caching.
         * @param maxH The maximium scale in the horizontal direction to use before punting and redrawing from scratch.
         *             For example, if maxH is 2, then we will attempt to scale any cached images up to 2x the canvas
         *             width before redrawing from scratch. Reasonable maxH values may improve painting performance.
         *             If set too high, then you may get poor looking graphics at higher zoom levels. Must be >= 1.
         * @param maxV The maximium scale in the vertical direction to use before punting and redrawing from scratch.
         *             For example, if maxV is 2, then we will attempt to scale any cached images up to 2x the canvas
         *             height before redrawing from scratch. Reasonable maxV values may improve painting performance.
         *             If set too high, then you may get poor looking graphics at higher zoom levels. Must be >= 1.
         */
        public PaintContext(Insets insets, Dimension canvasSize, boolean inverted,
                            CacheMode cacheMode, double maxH, double maxV) {
            if (maxH < 1 || maxH < 1) {
                throw new IllegalArgumentException("Both maxH and maxV must be >= 1");
            }

            this.stretchingInsets = insets == null ? EMPTY_INSETS : insets;
            this.canvasSize = canvasSize;
            this.inverted = inverted;
            this.cacheMode = cacheMode == null ? CacheMode.NO_CACHING : cacheMode;
            this.maxHorizontalScaleFactor = maxH;
            this.maxVerticalScaleFactor = maxV;

            if (canvasSize != null) {
                a = insets.left;
                b = canvasSize.width - insets.right;
                c = insets.top;
                d = canvasSize.height - insets.bottom;
                this.canvasSize = canvasSize;
                this.inverted = inverted;
                if (inverted) {
                    float available = canvasSize.width - (b - a);
                    aPercent = available > 0f ? a / available : 0f;
                    bPercent = available > 0f ? b / available : 0f;
                    available = canvasSize.height - (d - c);
                    cPercent = available > 0f ? c / available : 0f;
                    dPercent = available > 0f ? d / available : 0f;
                }
            }
        }
    }

    //---------------------- private methods

    //initializes the class to prepare it for being able to decode points
    private void prepare(float w, float h) {
        //if no PaintContext has been specified, reset the values and bail
        //also bail if the canvasSize was not set (since decoding will not work)
        if (ctx == null || ctx.canvasSize == null) {
            f = 1f;
            leftWidth = centerWidth = rightWidth = 0f;
            topHeight = centerHeight = bottomHeight = 0f;
            leftScale = centerHScale = rightScale = 0f;
            topScale = centerVScale = bottomScale = 0f;
            return;
        }

        //calculate the scaling factor, and the sizes for the various 9-square sections
        Number scale = (Number)UIManager.get("scale");
        f = scale == null ? 1f : scale.floatValue();

        if (ctx.inverted) {
            centerWidth = (ctx.b - ctx.a) * f;
            float availableSpace = w - centerWidth;
            leftWidth = availableSpace * ctx.aPercent;
            rightWidth = availableSpace * ctx.bPercent;
            centerHeight = (ctx.d - ctx.c) * f;
            availableSpace = h - centerHeight;
            topHeight = availableSpace * ctx.cPercent;
            bottomHeight = availableSpace * ctx.dPercent;
        } else {
            leftWidth = ctx.a * f;
            rightWidth = (float)(ctx.canvasSize.getWidth() - ctx.b) * f;
            centerWidth = w - leftWidth - rightWidth;
            topHeight = ctx.c * f;
            bottomHeight = (float)(ctx.canvasSize.getHeight() - ctx.d) * f;
            centerHeight = h - topHeight - bottomHeight;
        }

        leftScale = ctx.a == 0f ? 0f : leftWidth / ctx.a;
        centerHScale = (ctx.b - ctx.a) == 0f ? 0f : centerWidth / (ctx.b - ctx.a);
        rightScale = (ctx.canvasSize.width - ctx.b) == 0f ? 0f : rightWidth / (ctx.canvasSize.width - ctx.b);
        topScale = ctx.c == 0f ? 0f : topHeight / ctx.c;
        centerVScale = (ctx.d - ctx.c) == 0f ? 0f : centerHeight / (ctx.d - ctx.c);
        bottomScale = (ctx.canvasSize.height - ctx.d) == 0f ? 0f : bottomHeight / (ctx.canvasSize.height - ctx.d);
    }

    private void paintWith9SquareCaching(Graphics2D g, PaintContext ctx,
                                         JComponent c, int w, int h,
                                         Object[] extendedCacheKeys) {
        // check if we can scale to the requested size
        Dimension canvas = ctx.canvasSize;
        Insets insets = ctx.stretchingInsets;

        if (w <= (canvas.width * ctx.maxHorizontalScaleFactor) && h <= (canvas.height * ctx.maxVerticalScaleFactor)) {
            // get image at canvas size
            VolatileImage img = getImage(g.getDeviceConfiguration(), c, canvas.width, canvas.height, extendedCacheKeys);
            if (img != null) {
                // calculate dst inserts
                // todo: destination inserts need to take into acount scale factor for high dpi. Note: You can use f for this, I think
                Insets dstInsets;
                if (ctx.inverted){
                    int leftRight = (w-(canvas.width-(insets.left+insets.right)))/2;
                    int topBottom = (h-(canvas.height-(insets.top+insets.bottom)))/2;
                    dstInsets = new Insets(topBottom,leftRight,topBottom,leftRight);
                } else {
                    dstInsets = insets;
                }
                // paint 9 square scaled
                Object oldScaleingHints = g.getRenderingHint(RenderingHints.KEY_INTERPOLATION);
                g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                ImageScalingHelper.paint(g, 0, 0, w, h, img, insets, dstInsets,
                        ImageScalingHelper.PaintType.PAINT9_STRETCH, ImageScalingHelper.PAINT_ALL);
                g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                    oldScaleingHints!=null?oldScaleingHints:RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
            } else {
                // render directly
                paint0(g, c, w, h, extendedCacheKeys);
            }
        } else {
            // paint directly
            paint0(g, c, w, h, extendedCacheKeys);
        }
    }

    private void paintWithFixedSizeCaching(Graphics2D g, JComponent c, int w,
                                           int h, Object[] extendedCacheKeys) {
        VolatileImage img = getImage(g.getDeviceConfiguration(), c, w, h, extendedCacheKeys);
        if (img != null) {
            //render cached image
            g.drawImage(img, 0, 0, null);
        } else {
            // render directly
            paint0(g, c, w, h, extendedCacheKeys);
        }
    }

    /** Gets the rendered image for this painter at the requested size, either from cache or create a new one */
    private VolatileImage getImage(GraphicsConfiguration config, JComponent c,
                                   int w, int h, Object[] extendedCacheKeys) {
        ImageCache imageCache = ImageCache.getInstance();
        //get the buffer for this component
        VolatileImage buffer = (VolatileImage) imageCache.getImage(config, w, h, this, extendedCacheKeys);

        int renderCounter = 0; //to avoid any potential, though unlikely, infinite loop
        do {
            //validate the buffer so we can check for surface loss
            int bufferStatus = VolatileImage.IMAGE_INCOMPATIBLE;
            if (buffer != null) {
                bufferStatus = buffer.validate(config);
            }

            //If the buffer status is incompatible or restored, then we need to re-render to the volatile image
            if (bufferStatus == VolatileImage.IMAGE_INCOMPATIBLE || bufferStatus == VolatileImage.IMAGE_RESTORED) {
                //if the buffer is null (hasn't been created), or isn't the right size, or has lost its contents,
                //then recreate the buffer
                if (buffer == null || buffer.getWidth() != w || buffer.getHeight() != h ||
                        bufferStatus == VolatileImage.IMAGE_INCOMPATIBLE) {
                    //clear any resources related to the old back buffer
                    if (buffer != null) {
                        buffer.flush();
                        buffer = null;
                    }
                    //recreate the buffer
                    buffer = config.createCompatibleVolatileImage(w, h,
                            Transparency.TRANSLUCENT);
                    // put in cache for future
                    imageCache.setImage(buffer, config, w, h, this, extendedCacheKeys);
                }
                //create the graphics context with which to paint to the buffer
                Graphics2D bg = buffer.createGraphics();
                //clear the background before configuring the graphics
                bg.setComposite(AlphaComposite.Clear);
                bg.fillRect(0, 0, w, h);
                bg.setComposite(AlphaComposite.SrcOver);
                configureGraphics(bg);
                // paint the painter into buffer
                paint0(bg, c, w, h, extendedCacheKeys);
                //close buffer graphics
                bg.dispose();
            }
        } while (buffer.contentsLost() && renderCounter++ < 3);
        // check if we failed
        if (renderCounter == 3) return null;
        // return image
        return buffer;
    }

    //convenience method which creates a temporary graphics object by creating a
    //clone of the passed in one, configuring it, drawing with it, disposing it.
    //These steps have to be taken to ensure that any hints set on the graphics
    //are removed subsequent to painting.
    private void paint0(Graphics2D g, JComponent c, int width, int height,
                        Object[] extendedCacheKeys) {
        prepare(width, height);
        g = (Graphics2D)g.create();
        configureGraphics(g);
        doPaint(g, c, width, height, extendedCacheKeys);
        g.dispose();
    }

    private float clamp(float value) {
        if (value < 0) {
            value = 0;
        } else if (value > 1) {
            value = 1;
        }
        return value;
    }

    private int clamp(int value) {
        if (value < 0) {
            value = 0;
        } else if (value > 255) {
            value = 255;
        }
        return value;
    }
}