软件项目技术点(6)——结合鼠标操作绘制动态canvas画布

我们创建一个类封装了所有鼠标需要处理的事件。

 1     export class MouseEventInfo {
 2         el: HTMLElement;
 3         onmouseDown: Function;
 4         ondragMove: Function;
 5         ondragUp: Function;
 6         onmouseMove: Function;
 7         onmouseUp: Function;
 8         mouseWheel: Function;
 9         onContextMenu: Function;
10         constructor(ele: any, mouseDown: Function, dragMove: Function, dragUp: Function, mouseMove: Function, mouseUp: Function, mouseWheel: Function, contexMenu: Function) {
11             this.el = ele;
12             this.onmouseDown = mouseDown || null;
13             this.ondragMove = dragMove || null;
14             this.ondragUp = dragUp || null;
15             this.onmouseMove = mouseMove || null;
16             this.onmouseUp = mouseUp || null;
17             this.mouseWheel = mouseWheel || null
18             this.onContextMenu = contexMenu;
19         }
20     }

MouseEventClass就是绑定事件的过程，我们这里只列出部分代码，未列出的事件绑定的部分同理。

  1     export class MouseEventClass {
  2         x: number;
  3         y: number;
  4         down: boolean;
  5         dragging: boolean;
  6         scroll: boolean;
  7         lastX: number;
  8         lastY: number;
  9         startX: number;
 10         startY: number;
 11         moveCount: number;
 12         eventInfo: MouseEventInfo;
 13         constructor(eInfo: MouseEventInfo) {
 14             this.moveCount = 0;
 15             this.x = 0;
 16             this.y = 0;
 17             this.lastX = 0;
 18             this.lastY = 0;
 19             this.startX = 0;
 20             this.startY = 0;
 21             this.down = false;
 22             this.eventInfo = eInfo;
 23             this.dragging = false;
 24             this.scroll = false;
 25 
 26             var on = impressEvent.on;
 27             var self = this;
 28             if (this.eventInfo.el) {
 29                 on(this.eventInfo.el, "mousedown", function (e) {
 30                     if (e.button == 1 || e.button == 2) {
 31                         e.preventDefault();
 32                         return false;
 33                     }
 34                     self.mousedownHandler(e);
 35 
 36                 });
 37                 (this.eventInfo.ondragMove || this.eventInfo.onmouseMove) && on(this.eventInfo.el, "mousemove", function (e) {
 38                     if (e.button == 1 || e.button == 2) {
 39                         e.preventDefault();
 40                         return false;
 41                     }
 42                     self.mousemoveHandler(e);
 43                 });
 44                 (this.eventInfo.ondragUp || this.eventInfo.onmouseUp) && on(this.eventInfo.el, "mouseup", function (e) {
 45                     if (e.button == 1 || e.button == 2) {
 46                         e.preventDefault();
 47                         return false;
 48                     }
 49                     self.mouseupHandler(e);
 50                 });
 51                 this.eventInfo.mouseWheel && on(this.eventInfo.el, "mousewheel", function (e) {
 52                     if (e.button == 1 || e.button == 2) {
 53                         e.preventDefault();
 54                         return false;
 55                     }
 56                     self.mouseWheelHandler(e);
 57                 });
 58                 this.eventInfo.onContextMenu && on(this.eventInfo.el, "contextmenu", function (e) {
 59                     if (e.button == 1) {
 60                         e.preventDefault();
 61                         return false;
 62                     }
 63                     e.preventDefault();
 64                     self.contextMenuHandler(e);
 65                 })
 66             };
 67         }
 68 
 69         mousedownHandler = function (evt: MouseEvent) {
 70             this.moveCount = 1;
 71             this.down = true;
 72             this.startX = evt.pageX;
 73             this.startY = evt.pageY;
 74             this.dragging = false;
 75             this.eventInfo.el && this.eventInfo.onmouseDown && (this.eventInfo.onmouseDown({
 76                 evt: evt,
 77                 target: this.eventInfo.el,
 78                 mouseX: this.startX - leftWidth,
 79                 mouseY: this.startY - topHeight - topAnimaitonHeight,
 80                 buttonCode: evt.button
 81             }));
 82             this.lastX = evt.pageX;
 83             this.lastY = evt.pageY;
 84         };
 85         mousemoveHandler = function (evt: MouseEvent) {
 86             this.moveCount++;
 87             this.x = evt.pageX;
 88             this.y = evt.pageY;
 89             if (this.down && (this.x - this.startX != 0 || this.y - this.startY != 0)) {
 90                 this.dragging = true;
 91             }
 92             if (this.dragging) {
 93                 this.eventInfo.ondragMove && this.eventInfo.ondragMove({
 94                     evt: evt,
 95                     isFirstMove: this.moveCount == 1 ? true : false,
 96                     mouseX: this.x - leftWidth,
 97                     mouseY: this.y - topHeight - topAnimaitonHeight,
 98                     downX: this.startX - leftWidth,
 99                     downY: this.startY - topHeight - topAnimaitonHeight,
100                     lastX: this.lastX - leftWidth,
101                     lastY: this.lastY - topHeight - topAnimaitonHeight,
102                     noRoteDiffX: this.x - this.lastX,
103                     noRoteDiffY: this.y - this.lastY,
104                     totalX: this.x - this.startX,
105                     totalY: this.y - this.startY
106                 })
107             } else {
108                 this.eventInfo.onmouseMove && this.eventInfo.onmouseMove({
109                     evt: evt,
110                     mouseX: this.x - leftWidth,
111                     mouseY: this.y - topHeight - topAnimaitonHeight,
112                     downX: this.startX - leftWidth,
113                     downY: this.startY - topHeight - topAnimaitonHeight,
114                     lastX: this.lastX - leftWidth,
115                     lastY: this.lastY - topHeight - topAnimaitonHeight,
116                     noRoteDiffX: this.x - this.lastX,
117                     noRoteDiffY: this.y - this.lastY,
118                     totalX: this.x - this.startX,
119                     totalY: this.y - this.startY
120                 })
121             }
122             this.lastX = evt.pageX;
123             this.lastY = evt.pageY;
124         };

如何使用上面我们创建的两个类呢

我们在使用的时候先将MouseEventInfo这个类初始化，然后再用MouseEventClass绑定事件。

this.mouseEventInfo = new Common.MouseEventInfo(document, this.mouseDown, this.dragMove, this.dragUp, this.mouseMove, this.mouseUp, this.mouseWheel, this.onContextMenu);
            
new Common.MouseEventClass(this.mouseEventInfo);

我们绑定事件的元素是document，操作软件的所有事件都会走我们绑定的以下函数：

当然最重要的操做画布的响应也依赖于我们的事件处理逻辑：

this.mouseDown：鼠标按下的事件处理逻辑，例如存储当前的鼠标值

this.dragMove：鼠标拖拽移动，例如移动某个元素或者移动画布

this.dragUp：鼠标松开（拖拽后松开鼠标），例如停止移动

this.mouseMove：鼠标移动（不是按住状态），例如让元素显示hover状态

this.mouseUp：鼠标松开（mousedown后马上松开），例如触发某个元素的编辑状态

this.mouseWheel：鼠标滚动，例如缩放画布

this.onContextMenu：鼠标点击右键，例如显示右键菜单

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原文地址：https://www.cnblogs.com/fangsmile/p/6273667.html