gwt ClientBundle context.drawImage不'；不显示图像？我的2D引擎_Image_Gwt_Canvas_Sprite_Clientbundle

gwt ClientBundle context.drawImage不'；不显示图像？我的2D引擎

image gwt canvas

gwt ClientBundle context.drawImage不'；不显示图像？我的2D引擎,image,gwt,canvas,sprite,clientbundle,Image,Gwt,Canvas,Sprite,Clientbundle,我的代码没有错误，但我看不到图像。图像与ClientBundle文件位于同一位置。对不起，有一段代码。事实上，我是GWT（以及Java）的新手。我自学。我进行了调试，看到映像已加载，所有类都已初始化，但画布到目前为止是空的。我使用NetBeans IDE 7.3。如果有人能给我一些关于如何启动这个代码的建议，我会很高兴的。首先谢谢你 \uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu

我的代码没有错误，但我看不到图像。图像与ClientBundle文件位于同一位置。对不起，有一段代码。事实上，我是GWT（以及Java）的新手。我自学。我进行了调试，看到映像已加载，所有类都已初始化，但画布到目前为止是空的。我使用NetBeans IDE 7.3。如果有人能给我一些关于如何启动这个代码的建议，我会很高兴的。首先谢谢你

\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu 图像位于同一文件夹中

package info.alexpi.client.engine2D; import com.google.gwt.core.client.GWT; import com.google.gwt.resources.client.ClientBundle; import com.google.gwt.resources.client.ImageResource; public interface ResourseInspector extends ClientBundle { public static final ResourseInspector INSTANCE = GWT.create(ResourseInspector.class); @ClientBundle.Source("image1.png") //GWT.getHostPageBaseURL() or GWT.getModuleBaseURL() - By the way, why it's not allowed to use here? ImageResource Img(); }
\uuuuuuuuuuuu点2D\uuuuuuuuu

package info.alexpi.client.engine2D; public class Point2D { public int x = 0; public int y = 0; }

package info.alexpi.client.engine2D; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.dom.client.ImageElement; public class Sprite2D { private Point2D pos = new Point2D(); private ImgElement2D img; private double scale; private Rect2D rect = new Rect2D(); public Sprite2D(ImgElement2D image2D){ this.img = image2D; this.rect = image2D.getRect(); this.scale = 1.0; this.pos.x = 0; this.pos.y = 0; } public void setImage(ImgElement2D image2D){ this.img = image2D; } public ImgElement2D getImgElement(){ return this.img; } ________________DRAWING ______________________ public void draw(Context2d context){ ImageElement el = this.img.getImg(); if( el != null) { context.drawImage(el, rect.x, rect.y, rect.w, rect.h, pos.x, pos.y, rect.w*scale, rect.h*scale); } }

package info.alexpi.client; import com.google.gwt.canvas.client.Canvas; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.canvas.dom.client.CssColor; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import info.alexpi.client.engine2D.ImgElement2D; import info.alexpi.client.engine2D.Point2D; import info.alexpi.client.engine2D.Rect2D; import info.alexpi.client.engine2D.ResourseInspector; import info.alexpi.client.engine2D.Sprite2D; import java.util.ArrayList; import java.util.List; public class gwtEntryPoint implements EntryPoint { static final String holderId = "canvasholder"; static final String upgradeMessage = "Your browser does not support the HTML5 Canvas. " + "Please upgrade your browser to view this demo."; Canvas canvas; Canvas backBuffer; Context2d context; Context2d backBufferContext; final CssColor redrawColor = CssColor.make("rgba(255,255,255,0.0)"); // canvas size, in px static final int height = 712; static final int width = 800; boolean isFirstLoading = true; // mouse positions relative to canvas int mouseX, mouseY; //timer refresh rate, in milliseconds static final int refreshRate = 25; String imgAddress = GWT.getHostPageBaseURL() + "resources/images/Anthony-Catwalk-Dress.png"; //String imgAddress = "resources/images/image1.png"; //Second place of image String cssAddress = GWT.getHostPageBaseURL() + "resources/myStyle.css"; double scale = 0.7; List<Sprite2D> spriteList = new ArrayList<Sprite2D>(); ImgElement2D im; public gwtEntryPoint() { } // init the canvases------------------------------------------------------------------------- void initCanvas(){ canvas = Canvas.createIfSupported(); backBuffer = Canvas.createIfSupported(); if (canvas == null) { RootPanel.get(holderId).add(new Label(upgradeMessage)); return; } canvas.setWidth(width + "px"); canvas.setHeight(height + "px"); canvas.setCoordinateSpaceWidth(width); canvas.setCoordinateSpaceHeight(height); backBuffer.setCoordinateSpaceWidth(width); backBuffer.setCoordinateSpaceHeight(height); canvas.setStyleName(cssAddress); //apply css style canvas.getElement().getStyle().setProperty("border", "3px solid #00F"); RootPanel.get(holderId).add(canvas); context = canvas.getContext2d(); backBufferContext = backBuffer.getContext2d(); } // draw backBuffer ---------------------------------------------------------------------------- public void drawBuffer(Context2d back, Context2d front){ front.drawImage(back.getCanvas(), 0, 0); } void initElements(){ im = new ImgElement2D(ResourseInspector.INSTANCE.Img()); //ImageResource loading Sprite2D sprite = new Sprite2D(im); Rect2D r = new Rect2D(0,0, 228, 720); //man sprite.setRect(r); spriteList.add(sprite); //im = new ImgElement2D(imgAddress); //another way of image loading (doesn't trigger) sprite = new Sprite2D(im); r = new Rect2D(226,12, 230, 283); //white T-shirt sprite.setRect(r); spriteList.add(sprite); } void doUpdate(){ // update the back canvas backBufferContext.setFillStyle(redrawColor); backBufferContext.fillRect(0, 0, width, height); for(int x = 0; x < spriteList.size(); ++x){ spriteList.get(x).draw(backBufferContext); // spriteList.get(x).draw(context); } drawBuffer(backBufferContext, context); } // init Assets & Timer ----------------------------------------------------------------------- void initAssets(){ initElements(); final Timer timer = new Timer() { @Override public void run() { doUpdate(); } }; timer.scheduleRepeating(refreshRate); } @Override public void onModuleLoad() { initCanvas(); initAssets(); } }
\uuuuuuRect2D\uuuuuuu

package info.alexpi.client.engine2D; public class Point2D { public int x = 0; public int y = 0; }

package info.alexpi.client.engine2D; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.dom.client.ImageElement; public class Sprite2D { private Point2D pos = new Point2D(); private ImgElement2D img; private double scale; private Rect2D rect = new Rect2D(); public Sprite2D(ImgElement2D image2D){ this.img = image2D; this.rect = image2D.getRect(); this.scale = 1.0; this.pos.x = 0; this.pos.y = 0; } public void setImage(ImgElement2D image2D){ this.img = image2D; } public ImgElement2D getImgElement(){ return this.img; } ________________DRAWING ______________________ public void draw(Context2d context){ ImageElement el = this.img.getImg(); if( el != null) { context.drawImage(el, rect.x, rect.y, rect.w, rect.h, pos.x, pos.y, rect.w*scale, rect.h*scale); } }

package info.alexpi.client; import com.google.gwt.canvas.client.Canvas; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.canvas.dom.client.CssColor; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import info.alexpi.client.engine2D.ImgElement2D; import info.alexpi.client.engine2D.Point2D; import info.alexpi.client.engine2D.Rect2D; import info.alexpi.client.engine2D.ResourseInspector; import info.alexpi.client.engine2D.Sprite2D; import java.util.ArrayList; import java.util.List; public class gwtEntryPoint implements EntryPoint { static final String holderId = "canvasholder"; static final String upgradeMessage = "Your browser does not support the HTML5 Canvas. " + "Please upgrade your browser to view this demo."; Canvas canvas; Canvas backBuffer; Context2d context; Context2d backBufferContext; final CssColor redrawColor = CssColor.make("rgba(255,255,255,0.0)"); // canvas size, in px static final int height = 712; static final int width = 800; boolean isFirstLoading = true; // mouse positions relative to canvas int mouseX, mouseY; //timer refresh rate, in milliseconds static final int refreshRate = 25; String imgAddress = GWT.getHostPageBaseURL() + "resources/images/Anthony-Catwalk-Dress.png"; //String imgAddress = "resources/images/image1.png"; //Second place of image String cssAddress = GWT.getHostPageBaseURL() + "resources/myStyle.css"; double scale = 0.7; List<Sprite2D> spriteList = new ArrayList<Sprite2D>(); ImgElement2D im; public gwtEntryPoint() { } // init the canvases------------------------------------------------------------------------- void initCanvas(){ canvas = Canvas.createIfSupported(); backBuffer = Canvas.createIfSupported(); if (canvas == null) { RootPanel.get(holderId).add(new Label(upgradeMessage)); return; } canvas.setWidth(width + "px"); canvas.setHeight(height + "px"); canvas.setCoordinateSpaceWidth(width); canvas.setCoordinateSpaceHeight(height); backBuffer.setCoordinateSpaceWidth(width); backBuffer.setCoordinateSpaceHeight(height); canvas.setStyleName(cssAddress); //apply css style canvas.getElement().getStyle().setProperty("border", "3px solid #00F"); RootPanel.get(holderId).add(canvas); context = canvas.getContext2d(); backBufferContext = backBuffer.getContext2d(); } // draw backBuffer ---------------------------------------------------------------------------- public void drawBuffer(Context2d back, Context2d front){ front.drawImage(back.getCanvas(), 0, 0); } void initElements(){ im = new ImgElement2D(ResourseInspector.INSTANCE.Img()); //ImageResource loading Sprite2D sprite = new Sprite2D(im); Rect2D r = new Rect2D(0,0, 228, 720); //man sprite.setRect(r); spriteList.add(sprite); //im = new ImgElement2D(imgAddress); //another way of image loading (doesn't trigger) sprite = new Sprite2D(im); r = new Rect2D(226,12, 230, 283); //white T-shirt sprite.setRect(r); spriteList.add(sprite); } void doUpdate(){ // update the back canvas backBufferContext.setFillStyle(redrawColor); backBufferContext.fillRect(0, 0, width, height); for(int x = 0; x < spriteList.size(); ++x){ spriteList.get(x).draw(backBufferContext); // spriteList.get(x).draw(context); } drawBuffer(backBufferContext, context); } // init Assets & Timer ----------------------------------------------------------------------- void initAssets(){ initElements(); final Timer timer = new Timer() { @Override public void run() { doUpdate(); } }; timer.scheduleRepeating(refreshRate); } @Override public void onModuleLoad() { initCanvas(); initAssets(); } }
\uuuuuuuuuuuuuuuuuuuuuuuuImgElement2D\uuuuuuuuuuuuuuuuu 我需要这个类来保持原始图像的宽度和高度

package info.alexpi.client.engine2D; import com.google.gwt.dom.client.ImageElement; import com.google.gwt.event.dom.client.ErrorEvent; import com.google.gwt.event.dom.client.ErrorHandler; import com.google.gwt.event.dom.client.LoadEvent; import com.google.gwt.event.dom.client.LoadHandler; import com.google.gwt.resources.client.ImageResource; import com.google.gwt.user.client.ui.Image; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; public class ImgElement2D { private Rect2D rect = new Rect2D(); private ImageElement imgElement; private Image tempImg; public ImgElement2D(String imgAddress){ try { Image.prefetch(imgAddress); tempImg = new Image(imgAddress); // SafeUri fromString = UriUtils.fromString(imgAddress); // tempImg.setUrl(fromString); //SafeUri url // this method doesn't trigger tempImg.addLoadHandler(new LoadHandler(){ @Override public void onLoad(LoadEvent event) { imgElement = (ImageElement) tempImg.getElement().cast(); rect.x = 0; rect.y = 0; rect.h = tempImg.getHeight(); rect.w = tempImg.getWidth(); //RootPanel.get().remove(image); } }); public ImgElement2D(ImageResource resource){ tempImg = new Image(resource); rect.x = 0; rect.y = 0; rect.h = tempImg.getHeight(); rect.w = tempImg.getWidth(); imgElement = (ImageElement) tempImg.getElement().cast(); }
\uuuuuuuuuuuu精灵2D\uuuuuuuuuuuu

package info.alexpi.client.engine2D; public class Point2D { public int x = 0; public int y = 0; }

package info.alexpi.client.engine2D; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.dom.client.ImageElement; public class Sprite2D { private Point2D pos = new Point2D(); private ImgElement2D img; private double scale; private Rect2D rect = new Rect2D(); public Sprite2D(ImgElement2D image2D){ this.img = image2D; this.rect = image2D.getRect(); this.scale = 1.0; this.pos.x = 0; this.pos.y = 0; } public void setImage(ImgElement2D image2D){ this.img = image2D; } public ImgElement2D getImgElement(){ return this.img; } ________________DRAWING ______________________ public void draw(Context2d context){ ImageElement el = this.img.getImg(); if( el != null) { context.drawImage(el, rect.x, rect.y, rect.w, rect.h, pos.x, pos.y, rect.w*scale, rect.h*scale); } }

package info.alexpi.client; import com.google.gwt.canvas.client.Canvas; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.canvas.dom.client.CssColor; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import info.alexpi.client.engine2D.ImgElement2D; import info.alexpi.client.engine2D.Point2D; import info.alexpi.client.engine2D.Rect2D; import info.alexpi.client.engine2D.ResourseInspector; import info.alexpi.client.engine2D.Sprite2D; import java.util.ArrayList; import java.util.List; public class gwtEntryPoint implements EntryPoint { static final String holderId = "canvasholder"; static final String upgradeMessage = "Your browser does not support the HTML5 Canvas. " + "Please upgrade your browser to view this demo."; Canvas canvas; Canvas backBuffer; Context2d context; Context2d backBufferContext; final CssColor redrawColor = CssColor.make("rgba(255,255,255,0.0)"); // canvas size, in px static final int height = 712; static final int width = 800; boolean isFirstLoading = true; // mouse positions relative to canvas int mouseX, mouseY; //timer refresh rate, in milliseconds static final int refreshRate = 25; String imgAddress = GWT.getHostPageBaseURL() + "resources/images/Anthony-Catwalk-Dress.png"; //String imgAddress = "resources/images/image1.png"; //Second place of image String cssAddress = GWT.getHostPageBaseURL() + "resources/myStyle.css"; double scale = 0.7; List<Sprite2D> spriteList = new ArrayList<Sprite2D>(); ImgElement2D im; public gwtEntryPoint() { } // init the canvases------------------------------------------------------------------------- void initCanvas(){ canvas = Canvas.createIfSupported(); backBuffer = Canvas.createIfSupported(); if (canvas == null) { RootPanel.get(holderId).add(new Label(upgradeMessage)); return; } canvas.setWidth(width + "px"); canvas.setHeight(height + "px"); canvas.setCoordinateSpaceWidth(width); canvas.setCoordinateSpaceHeight(height); backBuffer.setCoordinateSpaceWidth(width); backBuffer.setCoordinateSpaceHeight(height); canvas.setStyleName(cssAddress); //apply css style canvas.getElement().getStyle().setProperty("border", "3px solid #00F"); RootPanel.get(holderId).add(canvas); context = canvas.getContext2d(); backBufferContext = backBuffer.getContext2d(); } // draw backBuffer ---------------------------------------------------------------------------- public void drawBuffer(Context2d back, Context2d front){ front.drawImage(back.getCanvas(), 0, 0); } void initElements(){ im = new ImgElement2D(ResourseInspector.INSTANCE.Img()); //ImageResource loading Sprite2D sprite = new Sprite2D(im); Rect2D r = new Rect2D(0,0, 228, 720); //man sprite.setRect(r); spriteList.add(sprite); //im = new ImgElement2D(imgAddress); //another way of image loading (doesn't trigger) sprite = new Sprite2D(im); r = new Rect2D(226,12, 230, 283); //white T-shirt sprite.setRect(r); spriteList.add(sprite); } void doUpdate(){ // update the back canvas backBufferContext.setFillStyle(redrawColor); backBufferContext.fillRect(0, 0, width, height); for(int x = 0; x < spriteList.size(); ++x){ spriteList.get(x).draw(backBufferContext); // spriteList.get(x).draw(context); } drawBuffer(backBufferContext, context); } // init Assets & Timer ----------------------------------------------------------------------- void initAssets(){ initElements(); final Timer timer = new Timer() { @Override public void run() { doUpdate(); } }; timer.scheduleRepeating(refreshRate); } @Override public void onModuleLoad() { initCanvas(); initAssets(); } }
主要入口点

package info.alexpi.client.engine2D; public class Point2D { public int x = 0; public int y = 0; }

package info.alexpi.client.engine2D; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.dom.client.ImageElement; public class Sprite2D { private Point2D pos = new Point2D(); private ImgElement2D img; private double scale; private Rect2D rect = new Rect2D(); public Sprite2D(ImgElement2D image2D){ this.img = image2D; this.rect = image2D.getRect(); this.scale = 1.0; this.pos.x = 0; this.pos.y = 0; } public void setImage(ImgElement2D image2D){ this.img = image2D; } public ImgElement2D getImgElement(){ return this.img; } ________________DRAWING ______________________ public void draw(Context2d context){ ImageElement el = this.img.getImg(); if( el != null) { context.drawImage(el, rect.x, rect.y, rect.w, rect.h, pos.x, pos.y, rect.w*scale, rect.h*scale); } }

package info.alexpi.client; import com.google.gwt.canvas.client.Canvas; import com.google.gwt.canvas.dom.client.Context2d; import com.google.gwt.canvas.dom.client.CssColor; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.user.client.Timer; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import info.alexpi.client.engine2D.ImgElement2D; import info.alexpi.client.engine2D.Point2D; import info.alexpi.client.engine2D.Rect2D; import info.alexpi.client.engine2D.ResourseInspector; import info.alexpi.client.engine2D.Sprite2D; import java.util.ArrayList; import java.util.List; public class gwtEntryPoint implements EntryPoint { static final String holderId = "canvasholder"; static final String upgradeMessage = "Your browser does not support the HTML5 Canvas. " + "Please upgrade your browser to view this demo."; Canvas canvas; Canvas backBuffer; Context2d context; Context2d backBufferContext; final CssColor redrawColor = CssColor.make("rgba(255,255,255,0.0)"); // canvas size, in px static final int height = 712; static final int width = 800; boolean isFirstLoading = true; // mouse positions relative to canvas int mouseX, mouseY; //timer refresh rate, in milliseconds static final int refreshRate = 25; String imgAddress = GWT.getHostPageBaseURL() + "resources/images/Anthony-Catwalk-Dress.png"; //String imgAddress = "resources/images/image1.png"; //Second place of image String cssAddress = GWT.getHostPageBaseURL() + "resources/myStyle.css"; double scale = 0.7; List<Sprite2D> spriteList = new ArrayList<Sprite2D>(); ImgElement2D im; public gwtEntryPoint() { } // init the canvases------------------------------------------------------------------------- void initCanvas(){ canvas = Canvas.createIfSupported(); backBuffer = Canvas.createIfSupported(); if (canvas == null) { RootPanel.get(holderId).add(new Label(upgradeMessage)); return; } canvas.setWidth(width + "px"); canvas.setHeight(height + "px"); canvas.setCoordinateSpaceWidth(width); canvas.setCoordinateSpaceHeight(height); backBuffer.setCoordinateSpaceWidth(width); backBuffer.setCoordinateSpaceHeight(height); canvas.setStyleName(cssAddress); //apply css style canvas.getElement().getStyle().setProperty("border", "3px solid #00F"); RootPanel.get(holderId).add(canvas); context = canvas.getContext2d(); backBufferContext = backBuffer.getContext2d(); } // draw backBuffer ---------------------------------------------------------------------------- public void drawBuffer(Context2d back, Context2d front){ front.drawImage(back.getCanvas(), 0, 0); } void initElements(){ im = new ImgElement2D(ResourseInspector.INSTANCE.Img()); //ImageResource loading Sprite2D sprite = new Sprite2D(im); Rect2D r = new Rect2D(0,0, 228, 720); //man sprite.setRect(r); spriteList.add(sprite); //im = new ImgElement2D(imgAddress); //another way of image loading (doesn't trigger) sprite = new Sprite2D(im); r = new Rect2D(226,12, 230, 283); //white T-shirt sprite.setRect(r); spriteList.add(sprite); } void doUpdate(){ // update the back canvas backBufferContext.setFillStyle(redrawColor); backBufferContext.fillRect(0, 0, width, height); for(int x = 0; x < spriteList.size(); ++x){ spriteList.get(x).draw(backBufferContext); // spriteList.get(x).draw(context); } drawBuffer(backBufferContext, context); } // init Assets & Timer ----------------------------------------------------------------------- void initAssets(){ initElements(); final Timer timer = new Timer() { @Override public void run() { doUpdate(); } }; timer.scheduleRepeating(refreshRate); } @Override public void onModuleLoad() { initCanvas(); initAssets(); } }

package info.alexpi.client；导入com.google.gwt.canvas.client.canvas；导入com.google.gwt.canvas.dom.client.Context2d；导入com.google.gwt.canvas.dom.client.CssColor；导入com.google.gwt.core.client.EntryPoint；导入com.google.gwt.core.client.gwt；导入com.google.gwt.event.dom.client.ClickEvent；导入com.google.gwt.event.dom.client.ClickHandler；导入com.google.gwt.user.client.Timer；导入com.google.gwt.user.client.ui.Label；导入com.google.gwt.user.client.ui.RootPanel；导入info.alexpi.client.engine2D.ImgElement2D；导入info.alexpi.client.engine2D.Point2D；导入info.alexpi.client.engine2D.Rect2D；导入info.alexpi.client.engine2D.resourcesinspector；导入info.alexpi.client.engine2D.Sprite2D；导入java.util.ArrayList；导入java.util.List；公共类gEventryPoint实现入口点{ 静态最终字符串持有者ID=“canvasholder”；静态最终字符串upgradeMessage=“您的浏览器不支持HTML5画布。” +“请升级浏览器以查看此演示。”；帆布；帆布背垫；语境； Context2d backBufferContext；最终CssColor redrawColor=CssColor.make（“rgba（255255,0.0）”）； //画布大小，以像素为单位静态最终内部高度=712；静态最终整数宽度=800；布尔值isFirstLoading=true； //相对于画布的鼠标位置 int mouseX，mouseY； //计时器刷新率，以毫秒为单位静态最终整型刷新率=25；字符串imgAddress=GWT.getHostPageBaseURL（）+“resources/images/Anthony Catwalk Dress.png”； //字符串imgAddress=“resources/images/image1.png”；//图像的第二位字符串cssAddress=GWT.getHostPageBaseURL（）+“resources/myStyle.css”；双刻度=0.7； List spriteList=new ArrayList（）； imgelement2dim；公共gwtEntryPoint（）{ } //在画布上------------------------------------------------------------------------- void initCanvas（）{ canvas=canvas.createIfSupported（）； backBuffer=Canvas.createIfSupported（）； if（canvas==null）{ get（holderId）.add（新标签（upgradeMessage））；返回； } canvas.setWidth（宽度+px）； canvas.setHeight（高度+px）； canvas.setCoordinateSpaceWidth（宽度）； canvas.setCoordinateSpaceHeight（高度）； backBuffer.setCoordinateSpaceWidth（宽度）； Backuffer.setCoordinateSpaceHeight（高度）； canvas.setStyleName（cssAddress）；//应用css样式 canvas.getElement（）.getStyle（）.setProperty（“border”，“3px solid#00F”）； get（holderId）.add（canvas）； context=canvas.getContext2d（）； backBufferContext=backBuffer.getContext2d（）； } //拉回缓冲器---------------------------------------------------------------------------- 公共空白提取缓冲区（Context2d背面，Context2d正面）{ front.drawImage（back.getCanvas（），0,0）； } void initElements（）{ im=new-ImgElement2D（resourcesinspector.INSTANCE.Img（））；//图像资源加载 Sprite2D sprite=新Sprite2D（im）； rect2dr=新的Rect2D（0,0228720）；//人雪碧。setRect（r）；精灵列表。添加（精灵）； //im=新的ImgElement2D（imgAddress）；//另一种图像加载方式（不触发）精灵=新精灵2D（im）； r=新的Rect2D（226,1230283）；//白色T恤雪碧。setRect（r）；精灵列表。添加（精灵）； } void doUpdate（）{ //更新后画布 backBufferContext.setFillStyle（重画颜色）； backBufferContext.fillRect（0，0，宽度，高度）；对于（int x=0；x
请参见这是因为，当前，新图像（imageResource）使用空白GIF并将图像资源作为背景图像。这已在master中修复，并将在今年晚些时候在GWT 2.6中发布。解决方法是使用新图像（imageResource.getSafeUri（））。在IE6/7中使用sprited图像是不安全的，但是那里不支持canvas，所以在这种情况下这不是一个真正的问题（注意，您可以将任何排列配置为使用sprited图像，而不是数据： URL，所以从技术上讲，使用getSafeUri（）是不安全的在任何浏览器中；GWT 2.6将添加一个isStandalone（）方法来告诉您何时可以安全使用它，这就是新建图像（imageResource）