shadowfactory.java

JAVA图形特效,详细介绍SWING等的效果开发

    public float getOpacity() {
        return opacity;
    }

    /**
     * <p>Sets the opacity used by the factory to generate shadows.</p>
     * <p>Consecutive calls to {@link #createShadow} will all use this color
     * until it is set again.</p>
     * <p>The opacity is comprised between 0.0f and 1.0f; 0.0f being fully
     * transparent and 1.0f fully opaque. If you provide a value out of these
     * boundaries, it will be restrained to the closest boundary.</p>
     * @param shadowOpacity the generated shadows opacity
     */
    public void setOpacity(final float shadowOpacity) {
        float oldOpacity = this.opacity;
        
        if (shadowOpacity < 0.0) {
            this.opacity = 0.0f;
        } else if (shadowOpacity > 1.0f) {
            this.opacity = 1.0f;
        } else {
            this.opacity = shadowOpacity;
        }
        
        changeSupport.firePropertyChange(OPACITY_CHANGED_PROPERTY,
                                         new Float(oldOpacity),
                                         new Float(this.opacity));
    }

    /**
     * <p>Gets the size in pixel used by the factory to generate shadows.</p>
     * @return this factory's shadow size
     */
    public int getSize() {
        return size;
    }

    /**
     * <p>Sets the size, in pixels, used by the factory to generate shadows.</p>
     * <p>The size defines the blur radius applied to the shadow to create the
     * fuzziness.</p>
     * <p>There is virtually no limit to the size but it has an impact on shadow
     * generation performances. The greater this value, the longer it will take 
     * to generate the shadow. Remember the generated shadow image dimensions 
     * are computed as follow:
     * <ul>
     *   <li>new width = original width + 2 * shadow size</li>
     *   <li>new height = original height + 2 * shadow size</li>
     * </ul>
     * The size cannot be negative. If you provide a negative value, the size
     * will be 0 instead.</p>
     * @param shadowSize the generated shadows size in pixels (fuzziness)
     */
    public void setSize(final int shadowSize) {
        int oldSize = this.size;
        
        if (shadowSize < 0) {
            this.size = 0;
        } else {
            this.size = shadowSize;
        }
        
        changeSupport.firePropertyChange(SIZE_CHANGED_PROPERTY,
                                         new Integer(oldSize),
                                         new Integer(this.size));
    }

    /**
     * <p>Generates the shadow for a given picture and the current properties
     * of the factory.</p>
     * <p>The generated shadow image dimensions are computed as follow:
     *  <ul>
     *  <li>new width = original width + 2 * shadow size</li>
     *  <li>new height = original height + 2 * shadow size</li>
     * </ul></p>
     * <p>The time taken by a call to this method depends on the size of the
     * shadow, the larger the longer it takes, and on the selected rendering
     * algorithm.</p>
     * @param image the picture from which the shadow must be cast
     * @return the picture containing the shadow of <code>image</code> 
     */
    public BufferedImage createShadow(final BufferedImage image) {
        if (hints.get(KEY_BLUR_QUALITY) == VALUE_BLUR_QUALITY_HIGH) {
            // the high quality algorithm is a 3-pass algorithm
            // it goes through all the pixels of the original picture at least
            // three times to generate the shadow
            // it is easy to understand but very slow
            BufferedImage subject = prepareImage(image);
            BufferedImage shadow = new BufferedImage(subject.getWidth(),
                                                     subject.getHeight(),
                                                     BufferedImage.TYPE_INT_ARGB);
            BufferedImage shadowMask = createShadowMask(subject);
            getLinearBlurOp(size).filter(shadowMask, shadow);
            return shadow;
        }

        // call the fast rendering algorithm
        return createShadowFast(image);
    }
    
    // prepares the picture for the high quality rendering algorithm
    private BufferedImage prepareImage(final BufferedImage image) {
        BufferedImage subject = new BufferedImage(image.getWidth() + size * 2,
                                                  image.getHeight() + size * 2,
                                                  BufferedImage.TYPE_INT_ARGB);

        Graphics2D g2 = subject.createGraphics();
        g2.drawImage(image, null, size, size);
        g2.dispose();

        return subject;
    }

    // fast rendering algorithm
    // basically applies duplicates the picture and applies a size*size kernel
    // in only one pass.
    // the kernel is simulated by an horizontal and a vertical pass
    // implemented by S閎astien Petrucci
    private BufferedImage createShadowFast(final BufferedImage src) {
        int shadowSize = this.size;

        int srcWidth = src.getWidth();
        int srcHeight = src.getHeight();

        int dstWidth = srcWidth + size;
        int dstHeight = srcHeight + size;

        int left = (shadowSize - 1) >> 1;
        int right = shadowSize - left;

        int yStop = dstHeight - right;

        BufferedImage dst = new BufferedImage(dstWidth, dstHeight,
                                              BufferedImage.TYPE_INT_ARGB);

        int shadowRgb = color.getRGB() & 0x00FFFFFF;

        int[] aHistory = new int[shadowSize];
        int historyIdx;

        int aSum;

        ColorModel srcColorModel = src.getColorModel();
        WritableRaster srcRaster = src.getRaster();
        int[] dstBuffer = ((DataBufferInt) dst.getRaster().getDataBuffer()).getData();

        int lastPixelOffset = right * dstWidth;
        float hSumDivider = 1.0f / size;
        float vSumDivider = opacity / size;

        // horizontal pass : extract the alpha mask from the source picture and
        // blur it into the destination picture
        for (int srcY = 0, dstOffset = left * dstWidth; srcY < srcHeight; srcY++) {

            // first pixels are empty
            for (historyIdx = 0; historyIdx < shadowSize; ) {
                aHistory[historyIdx++] = 0;
            }

            aSum = 0;
            historyIdx = 0;

            // compute the blur average with pixels from the source image
            for (int srcX = 0; srcX < srcWidth; srcX++) {

                int a = (int) (aSum * hSumDivider); // calculate alpha value
                dstBuffer[dstOffset++] = a << 24;   // store the alpha value only
                                                    // the shadow color will be added in the next pass

                aSum -= aHistory[historyIdx]; // substract the oldest pixel from the sum

                // extract the new pixel ...
                a = srcColorModel.getAlpha(srcRaster.getDataElements(srcX, srcY, null));
                aHistory[historyIdx] = a;   // ... and store its value into history
                aSum += a;                  // ... and add its value to the sum

                if (++historyIdx >= shadowSize) {
                    historyIdx -= shadowSize;
                }
            }

            // blur the end of the row - no new pixels to grab
            for (int i = 0; i < shadowSize; i++) {

                int a = (int) (aSum * hSumDivider);
                dstBuffer[dstOffset++] = a << 24;

                // substract the oldest pixel from the sum ... and nothing new to add !
                aSum -= aHistory[historyIdx];

                if (++historyIdx >= shadowSize) {
                    historyIdx -= shadowSize;
                }
            }
        }

        // vertical pass
        for (int x = 0, bufferOffset = 0; x < dstWidth; x++, bufferOffset = x) {

            aSum = 0;

            // first pixels are empty
            for (historyIdx = 0; historyIdx < left;) {
                aHistory[historyIdx++] = 0;
            }

            // and then they come from the dstBuffer
            for (int y = 0; y < right; y++, bufferOffset += dstWidth) {
                int a = dstBuffer[bufferOffset] >>> 24;         // extract alpha
                aHistory[historyIdx++] = a;                     // store into history
                aSum += a;                                      // and add to sum
            }

            bufferOffset = x;
            historyIdx = 0;

            // compute the blur average with pixels from the previous pass
            for (int y = 0; y < yStop; y++, bufferOffset += dstWidth) {

                int a = (int) (aSum * vSumDivider);             // calculate alpha value
                dstBuffer[bufferOffset] = a << 24 | shadowRgb;  // store alpha value + shadow color

                aSum -= aHistory[historyIdx];   // substract the oldest pixel from the sum

                a = dstBuffer[bufferOffset + lastPixelOffset] >>> 24;   // extract the new pixel ...
                aHistory[historyIdx] = a;                               // ... and store its value into history
                aSum += a;                                              // ... and add its value to the sum

                if (++historyIdx >= shadowSize) {
                    historyIdx -= shadowSize;
                }
            }

            // blur the end of the column - no pixels to grab anymore
            for (int y = yStop; y < dstHeight; y++, bufferOffset += dstWidth) {

                int a = (int) (aSum * vSumDivider);
                dstBuffer[bufferOffset] = a << 24 | shadowRgb;

                aSum -= aHistory[historyIdx];   // substract the oldest pixel from the sum

                if (++historyIdx >= shadowSize) {
                    historyIdx -= shadowSize;
                }
            }
        }

        return dst;
    }

    // creates the shadow mask for the original picture
    // it colorize all the pixels with the shadow color according to their
    // original transparency
    private BufferedImage createShadowMask(final BufferedImage image) {
        BufferedImage mask = new BufferedImage(image.getWidth(),
                                               image.getHeight(),
                                               BufferedImage.TYPE_INT_ARGB);

        Graphics2D g2d = mask.createGraphics();
        g2d.drawImage(image, 0, 0, null);
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_IN,
                                                    opacity));
        g2d.setColor(color);
        g2d.fillRect(0, 0, image.getWidth(), image.getHeight());
        g2d.dispose();

        return mask;
    }

    // creates a blur convolve operation by generating a kernel of
    // dimensions (size, size).
    private ConvolveOp getLinearBlurOp(final int size) {
        float[] data = new float[size * size];
        float value = 1.0f / (float) (size * size);
        for (int i = 0; i < data.length; i++) {
            data[i] = value;
        }
        return new ConvolveOp(new Kernel(size, size, data));
    }
}