SWT在画布上放置光标位置 [英] SWT drop cursor position on canvas

问题描述

我在JAVA中创建一个简单的绘制应用程序。我想要的是当人们点击画布，并进行拖放，一个监听器获取放置光标位置，但我不知道如何使一个下拉监听程序。当用户停止点击时，如何找到光标的位置？

I'm making a simple "paint" application in JAVA. I would have wanted that when the person clicks the canvas, and make a drag and drop, a listener get the drop cursor location, but I don't find how make a drop listener. How can I find the location of the cursor when the user stop his click?

我有以下代码拖动：

    Canvas paintC = new Canvas(shell, SWT.NONE);
    paintC.addDragDetectListener(new DragDetectListener() {
        public void dragDetected(DragDetectEvent arg0) {
            Point controlRelativePos = new Point(arg0.x, arg0.y);

            displayRelativePos1 = paintC.toDisplay(controlRelativePos);

            GC gc = new GC(paintC);

            gc.setBackground(SWTResourceManager.getColor(SWT.COLOR_YELLOW));
            gc.fillRectangle(arg0.x, arg0.y, 90, 60);

        }
    });

我应该使用拖曳功能才能取得最新排名吗？

Should I a drag function in order to get the latest position?

编辑：我试过这个，但它不工作：

I've tried this, but it didn't work :

dropTarget.addDropListener(new DropTargetAdapter() {
        @Override
        public void drop(DropTargetEvent event) {
            displayRelativePos2 = dropTarget.getDisplay().getCursorLocation();

            hauteur = displayRelativePos2.y - displayRelativePos1.y;
            largeur = displayRelativePos2.x - displayRelativePos1.x;

            GC gc = new GC(paintC);
            gc.setBackground(SWTResourceManager.getColor(SWT.COLOR_RED));
            gc.fillRectangle(displayRelativePos1.x, displayRelativePos1.y, largeur, hauteur);

            nbFormesAff = nbFormes +1;
            forme = "Rectangle" + nbFormesAff;
            pos = displayRelativePos1.x + ", " + displayRelativePos1.y +"\nhauteur:" + hauteur +" largeur:"+ largeur;

        }

推荐答案

DropTargetEvent 具有包含显示相对位置的 x 和 y

DropTargetEvent has x and y fields which contain the Display relative location of the cursor.

Point displayRelativeDrop = new Point(event.x, event.y);

您的 fillRectangle 必须使用相对到控件（paintC）不的显示。使用 Control.toControl（point）从显示相对于控件相对的转换。

Your fillRectangle must use points which are relative to the Control (paintC) not the display. Use Control.toControl(point) to convert from display relative to control relative.

在 drop 方法中绘制控件。只需在控件上调用 redraw ，然后在绘画监听器中绘制图形。

You should also not try to draw the control in the drop method. Just call redraw on the control and do the drawing in a paint listener.

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