Java tutorial
/******************************************************************************* * Copyright (c) 2006, 2016 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.examples.graphics; import org.eclipse.swt.SWT; import org.eclipse.swt.events.MouseEvent; import org.eclipse.swt.events.MouseListener; import org.eclipse.swt.events.MouseMoveListener; import org.eclipse.swt.graphics.Cursor; import org.eclipse.swt.graphics.Device; import org.eclipse.swt.graphics.Font; import org.eclipse.swt.graphics.GC; import org.eclipse.swt.graphics.Path; import org.eclipse.swt.graphics.Rectangle; import org.eclipse.swt.graphics.Transform; import org.eclipse.swt.widgets.Composite; /** * This tab presents cubic and quadratic curves that can be drawn. As a * demonstration, cubic and quadratic curves are used to spell out "SWT". * The user may reposition the cubic and quadratic handles. */ public class CurvesSWTTab extends GraphicsTab { /** These rectangles represent the handles on the curves. */ private Rectangle sRect1, sRect2, wRect1, wRect2, tTopRect1, tTopRect2, tBottomRect1, tBottomRect2; /** These values represent the positions of the curves. */ private float sXPos, sYPos, wXPos, wYPos, topTXPos, topTYPos, botTXPos, botTYPos; /** These values represent the x and y displacement of each handle. */ private float sDiffX1, sDiffY1, sDiffX2, sDiffY2; private float wDiffX1, wDiffY1, wDiffX2, wDiffY2; private float tTopDiffX1, tTopDiffY1, tTopDiffX2, tTopDiffY2; private float tBotDiffX1, tBotDiffY1, tBotDiffX2, tBotDiffY2; /** These are flags that indicate whether or not a handle has been moved. */ private boolean sLeftPtMoved, sRightPtMoved, wPt1Moved, wPt2Moved, tTopPt1Moved, tTopPt2Moved, tBotPt1Moved, tBotPt2Moved; private MouseMoveListener mouseMoveListener; private MouseListener mouseListener; private Cursor cursor; /** true if hovering over a handle, false otherwise */ private boolean hovering = false; /** true if left mouse button is held down, false otherwise */ private boolean mouseDown = false; public CurvesSWTTab(GraphicsExample example) { super(example); sRect1 = new Rectangle(-75, 50, 5, 5); sRect2 = new Rectangle(75, 100, 5, 5); sDiffX1 = sDiffY1 = 0; sDiffX2 = sDiffY2 = 0; wRect1 = new Rectangle(80, 300, 5, 5); wRect2 = new Rectangle(120, 300, 5, 5); wDiffX1 = wDiffY1 = wDiffX2 = wDiffY2 = 0; tTopRect1 = new Rectangle(33, -20, 5, 5); tTopRect2 = new Rectangle(66, 20, 5, 5); tTopDiffX1 = tTopDiffY1 = tTopDiffX2 = tTopDiffY2 = 0; tBottomRect1 = new Rectangle(-33, 50, 5, 5); tBottomRect2 = new Rectangle(33, 100, 5, 5); tBotDiffX1 = tBotDiffY1 = tBotDiffX2 = tBotDiffY2 = 0; } @Override public String getCategory() { return GraphicsExample.getResourceString("Curves"); //$NON-NLS-1$ } @Override public String getText() { return GraphicsExample.getResourceString("SWT"); //$NON-NLS-1$ } @Override public String getDescription() { return GraphicsExample.getResourceString("CurvesSWTDescription"); //$NON-NLS-1$ } @Override public boolean getDoubleBuffered() { return true; } @Override public void dispose() { if (mouseListener != null) example.canvas.removeMouseListener(mouseListener); if (mouseMoveListener != null) example.canvas.removeMouseMoveListener(mouseMoveListener); cursor = null; } /** * This helper method determines whether or not the cursor is positioned * over a handle. * * @param e * A MouseEvent * @return true if cursor is positioned over a handle; false otherwise */ private boolean isHovering(MouseEvent e) { Rectangle r1 = new Rectangle(sRect1.x + (int) sXPos - 1, sRect1.y + (int) sYPos - 1, sRect1.width + 2, sRect1.height + 2); Rectangle r2 = new Rectangle(sRect2.x + (int) sXPos - 1, sRect2.y + (int) sYPos - 1, sRect2.width + 2, sRect2.height + 2); Rectangle w1 = new Rectangle(wRect1.x + (int) wXPos - 1, wRect1.y + (int) wYPos - 1, wRect1.width + 2, wRect1.height + 2); Rectangle w2 = new Rectangle(wRect2.x + (int) wXPos - 1, wRect2.y + (int) wYPos - 1, wRect2.width + 2, wRect2.height + 2); Rectangle tTop1 = new Rectangle(tTopRect1.x + (int) topTXPos - 1, tTopRect1.y + (int) topTYPos - 1, tTopRect1.width + 2, tTopRect1.height + 2); Rectangle tTop2 = new Rectangle(tTopRect2.x + (int) topTXPos - 1, tTopRect2.y + (int) topTYPos - 1, tTopRect2.width + 2, tTopRect2.height + 2); Rectangle tBot1 = new Rectangle(tBottomRect1.x + (int) botTXPos - 1, tBottomRect1.y + (int) botTYPos - 1, tBottomRect1.width + 2, tBottomRect1.height + 2); Rectangle tBot2 = new Rectangle(tBottomRect2.x + (int) botTXPos - 1, tBottomRect2.y + (int) botTYPos - 1, tBottomRect2.width + 2, tBottomRect2.height + 2); return (r1.contains(e.x, e.y) || r2.contains(e.x, e.y) || w1.contains(e.x, e.y) || w2.contains(e.x, e.y) || tTop1.contains(e.x, e.y) || tTop2.contains(e.x, e.y) || tBot1.contains(e.x, e.y) || tBot2.contains(e.x, e.y)); } /** * Creates the widgets used to control the drawing. */ @Override public void createControlPanel(Composite parent) { if (cursor == null) { cursor = parent.getDisplay().getSystemCursor(SWT.CURSOR_HAND); } mouseMoveListener = e -> { if (hovering && mouseDown) { example.canvas.setCursor(cursor); } else if (isHovering(e)) { example.canvas.setCursor(cursor); hovering = true; } else { example.canvas.setCursor(null); hovering = false; } if (sLeftPtMoved) { sDiffX1 = sDiffX1 + e.x - (int) sXPos - sRect1.x; sDiffY1 = sDiffY1 + e.y - (int) sYPos - sRect1.y; sRect1.x = e.x - (int) sXPos; sRect1.y = e.y - (int) sYPos; } else if (sRightPtMoved) { sDiffX2 = sDiffX2 + e.x - (int) sXPos - sRect2.x; sDiffY2 = sDiffY2 + e.y - (int) sYPos - sRect2.y; sRect2.x = e.x - (int) sXPos; sRect2.y = e.y - (int) sYPos; } else if (wPt1Moved) { wDiffX1 = wDiffX1 + e.x - (int) wXPos - wRect1.x; wDiffY1 = wDiffY1 + e.y - (int) wYPos - wRect1.y; wRect1.x = e.x - (int) wXPos; wRect1.y = e.y - (int) wYPos; } else if (wPt2Moved) { wDiffX2 = wDiffX2 + e.x - (int) wXPos - wRect2.x; wDiffY2 = wDiffY2 + e.y - (int) wYPos - wRect2.y; wRect2.x = e.x - (int) wXPos; wRect2.y = e.y - (int) wYPos; } else if (tTopPt1Moved) { tTopDiffX1 = tTopDiffX1 + e.x - (int) topTXPos - tTopRect1.x; tTopDiffY1 = tTopDiffY1 + e.y - (int) topTYPos - tTopRect1.y; tTopRect1.x = e.x - (int) topTXPos; tTopRect1.y = e.y - (int) topTYPos; } else if (tTopPt2Moved) { tTopDiffX2 = tTopDiffX2 + e.x - (int) topTXPos - tTopRect2.x; tTopDiffY2 = tTopDiffY2 + e.y - (int) topTYPos - tTopRect2.y; tTopRect2.x = e.x - (int) topTXPos; tTopRect2.y = e.y - (int) topTYPos; } else if (tBotPt1Moved) { tBotDiffX1 = tBotDiffX1 + e.x - (int) botTXPos - tBottomRect1.x; tBotDiffY1 = tBotDiffY1 + e.y - (int) botTYPos - tBottomRect1.y; tBottomRect1.x = e.x - (int) botTXPos; tBottomRect1.y = e.y - (int) botTYPos; } else if (tBotPt2Moved) { tBotDiffX2 = tBotDiffX2 + e.x - (int) botTXPos - tBottomRect2.x; tBotDiffY2 = tBotDiffY2 + e.y - (int) botTYPos - tBottomRect2.y; tBottomRect2.x = e.x - (int) botTXPos; tBottomRect2.y = e.y - (int) botTYPos; } example.redraw(); }; mouseListener = new MouseListener() { @Override public void mouseDoubleClick(MouseEvent e) { } /** * Sent when a mouse button is pressed. * * @param e an event containing information about the mouse button press */ @Override public void mouseDown(MouseEvent e) { Rectangle r1 = new Rectangle(sRect1.x + (int) sXPos - 1, sRect1.y + (int) sYPos - 1, sRect1.width + 2, sRect1.height + 2); Rectangle r2 = new Rectangle(sRect2.x + (int) sXPos - 1, sRect2.y + (int) sYPos - 1, sRect2.width + 2, sRect2.height + 2); Rectangle w1 = new Rectangle(wRect1.x + (int) wXPos - 1, wRect1.y + (int) wYPos - 1, wRect1.width + 2, wRect1.height + 2); Rectangle w2 = new Rectangle(wRect2.x + (int) wXPos - 1, wRect2.y + (int) wYPos - 1, wRect2.width + 2, wRect2.height + 2); Rectangle tTop1 = new Rectangle(tTopRect1.x + (int) topTXPos - 1, tTopRect1.y + (int) topTYPos - 1, tTopRect1.width + 2, tTopRect1.height + 2); Rectangle tTop2 = new Rectangle(tTopRect2.x + (int) topTXPos - 1, tTopRect2.y + (int) topTYPos - 1, tTopRect2.width + 2, tTopRect2.height + 2); Rectangle tBot1 = new Rectangle(tBottomRect1.x + (int) botTXPos - 1, tBottomRect1.y + (int) botTYPos - 1, tBottomRect1.width + 2, tBottomRect1.height + 2); Rectangle tBot2 = new Rectangle(tBottomRect2.x + (int) botTXPos - 1, tBottomRect2.y + (int) botTYPos - 1, tBottomRect2.width + 2, tBottomRect2.height + 2); if (r1.contains(e.x, e.y)) { sLeftPtMoved = true; mouseDown = true; } else if (r2.contains(e.x, e.y)) { sRightPtMoved = true; mouseDown = true; } else if (w1.contains(e.x, e.y)) { wPt1Moved = true; mouseDown = true; } else if (w2.contains(e.x, e.y)) { wPt2Moved = true; mouseDown = true; } else if (tTop1.contains(e.x, e.y)) { tTopPt1Moved = true; mouseDown = true; } else if (tTop2.contains(e.x, e.y)) { tTopPt2Moved = true; mouseDown = true; } else if (tBot1.contains(e.x, e.y)) { tBotPt1Moved = true; mouseDown = true; } else if (tBot2.contains(e.x, e.y)) { tBotPt2Moved = true; mouseDown = true; } } /** * Sent when a mouse button is released. * * @param e an event containing information about the mouse button release */ @Override public void mouseUp(MouseEvent e) { mouseDown = false; if (isHovering(e)) { example.canvas.setCursor(cursor); } else { example.canvas.setCursor(null); } if (sLeftPtMoved) sLeftPtMoved = false; if (sRightPtMoved) sRightPtMoved = false; if (wPt1Moved) wPt1Moved = false; if (wPt2Moved) wPt2Moved = false; if (tTopPt1Moved) tTopPt1Moved = false; if (tTopPt2Moved) tTopPt2Moved = false; if (tBotPt1Moved) tBotPt1Moved = false; if (tBotPt2Moved) tBotPt2Moved = false; example.redraw(); } }; example.canvas.addMouseMoveListener(mouseMoveListener); example.canvas.addMouseListener(mouseListener); } @Override public void paint(GC gc, int width, int height) { if (!example.checkAdvancedGraphics()) return; Device device = gc.getDevice(); Font font = new Font(device, getPlatformFont(), 16, SWT.ITALIC); gc.setFont(font); gc.setLineWidth(2); Transform transform; // ----- letter s ----- sXPos = 4 * width / 16; sYPos = (height - 150) / 2; transform = new Transform(device); transform.translate(sXPos, sYPos); gc.setTransform(transform); transform.dispose(); gc.setForeground(device.getSystemColor(SWT.COLOR_DARK_BLUE)); gc.drawString(GraphicsExample.getResourceString("Cubic"), 0, 175, true); Path path = new Path(device); path.cubicTo(-200 + sDiffX1, 50 + sDiffY1, 200 + sDiffX2, 100 + sDiffY2, 0, 150); gc.drawPath(path); path.dispose(); // draw the spline points gc.setTransform(null); gc.drawRectangle(sRect1.x + (int) sXPos, sRect1.y + (int) sYPos, sRect1.width, sRect1.height); gc.drawRectangle(sRect2.x + (int) sXPos, sRect2.y + (int) sYPos, sRect2.width, sRect2.height); // ----- letter w ----- wXPos = 6 * width / 16; wYPos = (height - 150) / 2; transform = new Transform(device); transform.translate(wXPos, wYPos); gc.setTransform(transform); transform.dispose(); gc.setForeground(device.getSystemColor(SWT.COLOR_GRAY)); gc.drawString(GraphicsExample.getResourceString("Quadratic"), 0, -50, true); gc.drawString(GraphicsExample.getResourceString("Quadratic"), 110, -50, true); path = new Path(device); path.quadTo(100 + wDiffX1, 300 + wDiffY1, 100, 0); path.quadTo(100 + wDiffX2, 300 + wDiffY2, 200, 0); gc.drawPath(path); path.dispose(); gc.setTransform(null); gc.drawRectangle(wRect1.x + (int) wXPos, wRect1.y + (int) wYPos, wRect1.width, wRect1.height); gc.drawRectangle(wRect2.x + (int) wXPos, wRect2.y + (int) wYPos, wRect2.width, wRect2.height); // ----- top of letter t ----- topTXPos = 11 * width / 16; topTYPos = (height - 150) / 2; transform = new Transform(device); transform.translate(topTXPos, topTYPos); gc.setTransform(transform); transform.dispose(); gc.setForeground(device.getSystemColor(SWT.COLOR_YELLOW)); gc.drawString(GraphicsExample.getResourceString("Cubic"), 25, -50, true); path = new Path(device); path.cubicTo(33 + tTopDiffX1, -20 + tTopDiffY1, 66 + tTopDiffX2, 20 + tTopDiffY2, 100, 0); gc.drawPath(path); path.dispose(); gc.setTransform(null); gc.drawRectangle(tTopRect1.x + (int) topTXPos, tTopRect1.y + (int) topTYPos, tTopRect1.width, tTopRect1.height); gc.drawRectangle(tTopRect2.x + (int) topTXPos, tTopRect2.y + (int) topTYPos, tTopRect2.width, tTopRect2.height); // ----- vertical bar of letter t ----- botTXPos = 12 * width / 16; botTYPos = (height - 150) / 2; transform = new Transform(device); transform.translate(botTXPos, botTYPos); gc.setTransform(transform); transform.dispose(); gc.setForeground(device.getSystemColor(SWT.COLOR_RED)); gc.drawString(GraphicsExample.getResourceString("Cubic"), 0, 175, true); path = new Path(device); path.cubicTo(-33 + tBotDiffX1, 50 + tBotDiffY1, 33 + tBotDiffX2, 100 + tBotDiffY2, 0, 150); gc.drawPath(path); path.dispose(); gc.setTransform(null); gc.drawRectangle(tBottomRect1.x + (int) botTXPos, tBottomRect1.y + (int) botTYPos, tBottomRect1.width, tBottomRect1.height); gc.drawRectangle(tBottomRect2.x + (int) botTXPos, tBottomRect2.y + (int) botTYPos, tBottomRect2.width, tBottomRect2.height); font.dispose(); } /** * Returns the name of a valid font for the resident platform. */ static String getPlatformFont() { if (SWT.getPlatform() == "win32") { return "Arial"; } else if (SWT.getPlatform() == "gtk") { return "Baekmuk Batang"; } else { return "Verdana"; } } }