1 /* 2 * Copyright (C) 2009 The Android Open Source Project 3 * 4 * Licensed under the Eclipse Public License, Version 1.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.eclipse.org/org/documents/epl-v10.php 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.android.ide.eclipse.adt.internal.editors.layout.gle2; 17 18 import org.eclipse.swt.events.SelectionAdapter; 19 import org.eclipse.swt.events.SelectionEvent; 20 import org.eclipse.swt.widgets.ScrollBar; 21 22 /** 23 * Helper class to convert between control pixel coordinates and canvas coordinates. 24 * Takes care of the zooming and offset of the canvas. 25 */ 26 public class CanvasTransform { 27 /** 28 * Default margin around the rendered image, reduced 29 * when the contents do not fit. 30 */ 31 public static final int DEFAULT_MARGIN = 25; 32 33 /** 34 * The canvas which controls the zooming. 35 */ 36 private final LayoutCanvas mCanvas; 37 38 /** Canvas image size (original, before zoom), in pixels. */ 39 private int mImgSize; 40 41 /** Client size, in pixels. */ 42 private int mClientSize; 43 44 /** Left-top offset in client pixel coordinates. */ 45 private int mTranslate; 46 47 /** Current margin */ 48 private int mMargin = DEFAULT_MARGIN; 49 50 /** Scaling factor, > 0. */ 51 private double mScale; 52 53 /** Scrollbar widget. */ 54 private ScrollBar mScrollbar; 55 CanvasTransform(LayoutCanvas layoutCanvas, ScrollBar scrollbar)56 public CanvasTransform(LayoutCanvas layoutCanvas, ScrollBar scrollbar) { 57 mCanvas = layoutCanvas; 58 mScrollbar = scrollbar; 59 mScale = 1.0; 60 mTranslate = 0; 61 62 mScrollbar.addSelectionListener(new SelectionAdapter() { 63 @Override 64 public void widgetSelected(SelectionEvent e) { 65 // User requested scrolling. Changes translation and redraw canvas. 66 mTranslate = mScrollbar.getSelection(); 67 CanvasTransform.this.mCanvas.redraw(); 68 } 69 }); 70 mScrollbar.setIncrement(20); 71 } 72 73 /** 74 * Sets the new scaling factor. Recomputes scrollbars. 75 * @param scale Scaling factor, > 0. 76 */ setScale(double scale)77 public void setScale(double scale) { 78 if (mScale != scale) { 79 mScale = scale; 80 resizeScrollbar(); 81 } 82 } 83 84 /** 85 * Returns current scaling factor. 86 * 87 * @return The current scaling factor 88 */ getScale()89 public double getScale() { 90 return mScale; 91 } 92 93 /** 94 * Returns Canvas image size (original, before zoom), in pixels. 95 * 96 * @return Canvas image size (original, before zoom), in pixels 97 */ getImgSize()98 public int getImgSize() { 99 return mImgSize; 100 } 101 102 /** 103 * Returns the scaled image size in pixels. 104 * 105 * @return The scaled image size in pixels. 106 */ getScalledImgSize()107 public int getScalledImgSize() { 108 return (int) (mImgSize * mScale); 109 } 110 111 /** Changes the size of the canvas image and the client size. Recomputes scrollbars. */ setSize(int imgSize, int clientSize)112 public void setSize(int imgSize, int clientSize) { 113 mImgSize = imgSize; 114 setClientSize(clientSize); 115 } 116 117 /** Changes the size of the client size. Recomputes scrollbars. */ setClientSize(int clientSize)118 public void setClientSize(int clientSize) { 119 mClientSize = clientSize; 120 mScrollbar.setPageIncrement(clientSize); 121 resizeScrollbar(); 122 } 123 resizeScrollbar()124 private void resizeScrollbar() { 125 // scaled image size 126 int sx = (int) (mImgSize * mScale); 127 128 // Adjust margin such that for zoomed out views 129 // we don't waste space (unless the viewport is 130 // large enough to accommodate it) 131 int delta = mClientSize - sx; 132 if (delta < 0) { 133 mMargin = 0; 134 } else if (delta < 2 * DEFAULT_MARGIN) { 135 mMargin = delta / 2; 136 } else { 137 mMargin = DEFAULT_MARGIN; 138 } 139 140 // actual client area is always reduced by the margins 141 int cx = mClientSize - 2 * mMargin; 142 143 if (sx < cx) { 144 mTranslate = 0; 145 mScrollbar.setEnabled(false); 146 } else { 147 mScrollbar.setEnabled(true); 148 149 int selection = mScrollbar.getSelection(); 150 int thumb = cx; 151 int maximum = sx; 152 153 if (selection + thumb > maximum) { 154 selection = maximum - thumb; 155 if (selection < 0) { 156 selection = 0; 157 } 158 } 159 160 mScrollbar.setValues(selection, mScrollbar.getMinimum(), maximum, thumb, mScrollbar 161 .getIncrement(), mScrollbar.getPageIncrement()); 162 163 mTranslate = selection; 164 } 165 } 166 getMargin()167 public int getMargin() { 168 return mMargin; 169 } 170 translate(int canvasX)171 public int translate(int canvasX) { 172 return mMargin - mTranslate + (int) (mScale * canvasX); 173 } 174 scale(int canwasW)175 public int scale(int canwasW) { 176 return (int) (mScale * canwasW); 177 } 178 inverseTranslate(int screenX)179 public int inverseTranslate(int screenX) { 180 return (int) ((screenX - mMargin + mTranslate) / mScale); 181 } 182 } 183