com.googlecode.mgwt.image.client.ImageConverter.java Source code

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Here is the source code for com.googlecode.mgwt.image.client.ImageConverter.java

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/*
 * Copyright 2014 Daniel Kurka
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.googlecode.mgwt.image.client;

import com.google.gwt.canvas.client.Canvas;
import com.google.gwt.canvas.dom.client.CanvasPixelArray;
import com.google.gwt.canvas.dom.client.Context2d;
import com.google.gwt.canvas.dom.client.ImageData;
import com.google.gwt.dom.client.ImageElement;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.safehtml.shared.SafeUri;

public class ImageConverter {

    static class ConversionContext {
        Canvas canvas;
        Context2d context;
        CanvasPixelArray canvasPixelArray;
    }

    private interface LoadImageCallback {
        public void onSuccess(ImageElement imageElement);
    }

    public interface ImageConverterCallback {
        public void onSuccess(ImageResource imageResource);
    }

    private class ConvertedImageResource implements ImageResource {

        private final String dataUrl;
        private final int width;
        private final int height;

        public ConvertedImageResource(String dataUrl, int width, int height) {
            this.dataUrl = dataUrl;
            this.width = width;
            this.height = height;
        }

        @Override
        public String getName() {
            return "";
        }

        @Override
        public int getHeight() {
            return height;
        }

        @Override
        public int getLeft() {
            return 0;
        }

        @Override
        public SafeUri getSafeUri() {
            return new SafeUri() {

                @Override
                public String asString() {
                    return dataUrl;
                }

                @Override
                public int hashCode() {
                    return dataUrl.hashCode();
                }

                @Override
                public boolean equals(Object obj) {
                    return dataUrl.equals(obj);
                }
            };
        }

        @Override
        public int getTop() {
            return 0;
        }

        @Override
        public String getURL() {
            return dataUrl;
        }

        @Override
        public int getWidth() {
            return width;
        }

        @Override
        public boolean isAnimated() {
            return false;
        }
    }

    public void convert(final ImageResource resource, String color,
            final ImageConverterCallback imageConverterCallback) {

        if (color == null) {
            throw new IllegalArgumentException();
        }

        if (!color.startsWith("#")) {
            throw new IllegalArgumentException();
        }

        color = maybeExpandColor(color);

        final int hexColor = Integer.parseInt(color.substring(1), 16);

        final int red = hexColor >> 16 & 0xFF;
        final int green = hexColor >> 8 & 0xFF;
        final int blue = hexColor & 0xFF;

        final int height = resource.getHeight();
        final int width = resource.getWidth();

        loadImage(resource.getSafeUri().asString(), width, height, new LoadImageCallback() {

            @Override
            public void onSuccess(ImageElement imageElement) {

                Canvas canvas = Canvas.createIfSupported();
                canvas.getElement().setPropertyInt("height", height);
                canvas.getElement().setPropertyInt("width", width);

                Context2d context = canvas.getContext2d();
                context.drawImage(imageElement, 0, 0);
                ImageData imageData = context.getImageData(0, 0, width, height);

                CanvasPixelArray canvasPixelArray = imageData.getData();

                for (int i = 0; i < canvasPixelArray.getLength(); i += 4) {
                    canvasPixelArray.set(i, red);
                    canvasPixelArray.set(i + 1, green);
                    canvasPixelArray.set(i + 2, blue);
                    canvasPixelArray.set(i + 3, canvasPixelArray.get(i + 3));
                }
                context.putImageData(imageData, 0, 0);
                imageConverterCallback.onSuccess(new ConvertedImageResource(canvas.toDataUrl("image/png"),
                        resource.getWidth(), resource.getHeight()));
            }
        });
    }

    protected native void loadImage(String dataUrl, int width, int height, LoadImageCallback callback) /*-{
                                                                                                       var img = new Image();
                                                                                                       img.width = width;
                                                                                                       img.height = height;
                                                                                                       img.src = dataUrl;
                                                                                                       img.onload = $entry(function(){
                                                                                                       callback.@com.googlecode.mgwt.image.client.ImageConverter.LoadImageCallback::onSuccess(Lcom/google/gwt/dom/client/ImageElement;)(img);
                                                                                                       });
                                                                                                       img.onerror = function(e){
                                                                                                       @com.google.gwt.core.client.GWT::reportUncaughtException(Ljava/lang/Throwable;)(e);
                                                                                                       return true;
                                                                                                       };
                                                                                                       }-*/;

    private String maybeExpandColor(String color) {

        if (color.length() != 4) {
            return color;
        }

        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("#");
        stringBuilder.append(color.charAt(1));
        stringBuilder.append(color.charAt(1));
        stringBuilder.append(color.charAt(2));
        stringBuilder.append(color.charAt(2));
        stringBuilder.append(color.charAt(3));
        stringBuilder.append(color.charAt(3));
        return stringBuilder.toString();
    }
}