如何使用Ionic 2使图像可缩放

Question

我有一个只有一个图像的页面，如何使此图像可缩放？

我的页面

Answer 1

您可以将图像查看器用于Ionic 2+

• 安装

npm安装--保存离子img查看器

• 加载项app.module.ts

import { IonicImageViewerModule } from 'ionic-img-viewer';
@NgModule({
  declarations: [
    MyApp, 
    HomePage
  ],
  imports: [
    BrowserModule,
    IonicModule.forRoot(MyApp),
    IonicImageViewerModule
  ],

• 编程使用：

<img src="IMAGE_URL"#myImage（点击）="presentImage（myImage）"/>

import { ImageViewerController } from 'ionic-img-viewer';
export class MyPage {
  _imageViewerCtrl: ImageViewerController;
  constructor(imageViewerCtrl: ImageViewerController) {
    this._imageViewerCtrl = imageViewerCtrl;
  }
  presentImage(myImage) {
    const imageViewer = this._imageViewerCtrl.create(myImage);
    imageViewer.present(); 
  }
}

演示：演示离子img查看器

Answer 2

我在Ionic论坛上找到了这个解决方法：

html:

<ion-scroll (pinch)="pinchEvent($event)" scrollX="true" scrollY="true" zoom="true" style="width:100%;height:100%;text-align:center;">
    <div [ngStyle]="{'background':'url('+src+') no-repeat','width' : width + 'px', 'height' : height + 'px', 'transform' : 'rotate('+rotacion+'deg)', 'background-size' : 'contain', 'background-position' : 'center'}" style="margin-top:50px;margin-bottom:50px;"></div>
</ion-scroll>

.ts方法：

pinchEvent(e) {
    this.width = this.pinchW * e.scale;
    this.height = this.pinchH * e.scale;
    if(this.timeout == null){
        this.timeout = setTimeout(() => {
            this.timeout = null;
            this.updateWidthHeightPinch();
        }, 1000);
    } else {
        clearTimeout(this.timeout);
        this.timeout = setTimeout(() => {
            this.timeout = null;
            this.updateWidthHeightPinch();
        }, 1000);
    }
}
updateWidthHeightPinch() {
    this.pinchW = this.width;
    this.pinchH = this.height;
}

Answer 3

我自己编写了"捏"事件的代码-它非常简单（我用它来缩放建筑楼层地图）：

div class="floor-map"
     style="position: relative; left: 0px; top: 0px; height: 0px; overflow: hidden; cursor: move;"
     (touchstart)="mapMoveStart($event)"
     (touchend)="mapMoveStop($event)"
     (touchmove)="mapMove($event)"
     tappable
     #floorMapRef
> 
    <img [style.width]="width + 'px'"
         [style.height]="height + 'px'" ...>
</div>

在mapMove中，我有这样的东西：

pinchLenght = -1  // -1 means no pinch
...
mapMoveStart(event) {
    this.pinchLenght = -1; // "reset" pinch
    ...
}
mapMove(event) 
{
    if(event.touches.length==2) { // two fingers detection 
        let length = Math.abs(event.touches[0].clientX-event.touches[1].clientX)
              + Math.abs(event.touches[0].clientY-event.touches[1].clientY);
          if(this.pinchLenght < 0) { // case: first pinch "touch"
            this.pinchLenght = length
          } else {
            let delta = length - this.pinchLenght;
            this.pinchLenght = length;
            if(delta>0) {
              this.zoomMap(1.05);
            }
            if(delta<0) {
              this.zoomMap(0.95);
            }
         }
    }
    ...
}
...

在方法zoomMap(zoomFactor: number)中，我适当地改变了this.height和this.width（与<img>标签"绑定"）。