IOS limits the magnification of a picture by setting the zoom ratio of the pinch gesture
Last Update:2015-09-19
Source: Internet
Author: User
<span id="Label3"></p><p><p>Pinch gesture visual can enlarge the image infinitely, but in general, we only allow the user to zoom within a certain scale range</p></p><p><p>Scenario: records the total scale with a global value, and does not allow the range to continue after it is out of range, only back to the zoom range</p></p><p><p>If you bother packing a good <span style="font-size: 16px;"><strong>assortment</strong></span> here, Three lines of Code: Https://github.com/iOSSinger/SGZoomImage</p></p><p><p>The specific code is as Follows:</p></p><pre><span style="color: #0000ff;"><span style="color: #0000ff;">#import</span></span> <span style="color: #800000;"><span style="color: #800000;">"</span></span><span style="color: #800000;"><span style="color: #800000;">ViewController.h</span></span><span style="color: #800000;"><span style="color: #800000;">"</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">#define</span></span>Maxscale 2.0<span style="color: #008000;"><span style="color: #008000;">//</span></span><span style="color: #008000;"><span style="color: #008000;">Maximum zoom ratio</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">#define</span></span>Minscale 0.5<span style="color: #008000;"><span style="color: #008000;">//</span></span><span style="color: #008000;"><span style="color: #008000;">Minimum zoom ratio</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">#import</span></span> <span style="color: #800000;"><span style="color: #800000;">"</span></span><span style="color: #800000;"><span style="color: #800000;">uiimageview+zoom.h</span></span><span style="color: #800000;"><span style="color: #800000;">"</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">@interface</span></span><span style="color: #000000;"><span style="color: #000000;">viewcontroller () @property (weak, nonatomic) iboutlet uiimageview</span></span>*<span style="color: #000000;"><span style="color: #000000;">imageView; @property (nonatomic,assign) cgfloat totalscale;</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">@end</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">@implementation</span></span><span style="color: #000000;"><span style="color: #000000;">Viewcontroller</span></span>- (<span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span><span style="color: #000000;"><span style="color: #000000;">) Viewdidload {[super viewdidload]; Self.totalscale</span></span>=<span style="color: #800080;"><span style="color: #800080;">1.0</span></span><span style="color: #000000;"><span style="color: #000000;">; Uipinchgesturerecognizer</span></span>*pinch =<span style="color: #000000;"><span style="color: #000000;">[[uipinchgesturerecognizer alloc] initwithtarget:self action: @selector (pinch:)]; [self.imageview addgesturerecognizer:pinch]; }</span></span>- (<span style="color: #0000ff;"><span style="color: #0000ff;">void</span></span>) Pinch: (uipinchgesturerecognizer *<span style="color: #000000;"><span style="color: #000000;">) Recognizer{cgfloat</span> scale</span>=<span style="color: #000000;"><span style="color: #000000;">recognizer.scale; </span></span><span style="color: #008000;"><span style="color: #008000;">//</span></span><span style="color: #008000;"><span style="color: #008000;">Amplification Situation</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(scale ><span style="color: #800080;"><span style="color: #800080;">1.0</span></span><span style="color: #000000;"><span style="color: #000000;">){ </span></span><span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(self.totalscale > Maxscale)<span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span><span style="color: #000000;"><span style="color: #000000;">; } </span></span><span style="color: #008000;"><span style="color: #008000;">//</span></span><span style="color: #008000;"><span style="color: #008000;">reduce the situation</span></span> <span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(scale <<span style="color: #800080;"><span style="color: #800080;">1.0</span></span><span style="color: #000000;"><span style="color: #000000;">) { </span></span><span style="color: #0000ff;"><span style="color: #0000ff;">if</span></span>(self.totalscale < Minscale)<span style="color: #0000ff;"><span style="color: #0000ff;">return</span></span><span style="color: #000000;"><span style="color: #000000;">; } self.imageView.transform</span></span>=<span style="color: #000000;"><span style="color: #000000;">Cgaffinetransformscale (self.imageView.transform, scale, scale); Self.totalscale</span></span>*=<span style="color: #000000;">scale <span style="color: #000000;">; Recognizer.scale</span></span>=<span style="color: #800080;"><span style="color: #800080;">1.0</span></span><span style="color: #000000;"><span style="color: #000000;">; }</span></span><span style="color: #0000ff;"><span style="color: #0000ff;">@end</span></span></pre><p><p></p></p><p><p>IOS limits the magnification of a picture by setting the zoom ratio of the pinch gesture</p></p></span>
