png | 易学教程

How to add extra meta data to PNG?

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问题 is there a way to add some extra metadata to a PNG file and then retrieve it with PHP ? like Comment field. 回答1: If you have ImageMagick installed, it comes with two utilities: mogrify and identify. To add comments: $ mogrify.exe -comment "My test comment" plogo.png To retrieve comments: $ identify.exe -verbose plogo.png | grep -i "comment:" comment: My test comment I don't know if mogrify/identify functions are available as PHP libraries, but you can always use the php system command. 来源：

iPhone SDK: accessing indexed color PNG images

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问题 I'm interested in loading indexed-color PNG images in my iPhone application. Once they're loaded, I want to access the images on a per-pixel basis. In particular, I want to get the index of the color (rather than the color itself) of individual pixels. Unfortunately, there does not seem to be a way to access pixels via the UIImage class, let alone color index of a pixel. I'm also taking a look at Quartz2D-related APIs, but so far things look bleak. I'd greatly appreciate any suggestions. I'm

Adding a picture to plot in R

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问题 I'm trying to add a picture (jpeg,png doesn't care) to a plot which is defined by the layout function. For example: a<-c(1,2,3,4,5) b<-c(2,4,8,16,32) m <- matrix(c(1,1,1,1,2,3,2,3), nrow = 2, ncol = 4) layout(m); hist(a);boxplot(a~b);plot(b~a)* Instead of the histogram on position 1 I want to add an image (In my case it's a map) I don't know how to deal with the jpeg package, maybe you can help me! 回答1: You need to read your png or jpeg file through the png and jpeg packages. Then, with the

Set transparent background using ImageMagick and commandline prompt

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问题 Suppose you have any image (PNG or JPG). This image has a white background and I need to make this background transparent. I have tried with these examples: convert original.png -background none transparent.png convert original.png -background white -flatten -alpha off transparent.png but with no desirable results. How can I make it? IMPORTANT: Using convert command-line. 回答1: I am using ImageMagick 6.6.9-7 on Ubuntu 12.04. What worked for me was the following: convert test.png -transparent

CSS Border on PNG image with transparent parts

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问题 Im trying to add a border on a PNG image I have (Example included). The thing is that when I add the border currently it adds it on a box shape around all the image and not on the exact vector (Meaning it includes the transparent parts in the image). Is there any possible way to setup the configuration of the border that it won't consider the transparent area's. (Even if not in CSS... Maybe HTML5/JS?) 回答1: As of now ( January 31st 2015 ) there is a way to do that without using canvas, with

CSS Border on PNG image with transparent parts

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PNG Transparency Resize with SimpleImage.php Class

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问题 I'm using a modified version of the SimpleImage.php class: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php The edits I found on phpfreaks (http://www.phpfreaks.com/forums/index.php?topic=301811.0), but when I use, the png gets resized but the transparency is black. I make the call like: $max_width = 200; // set a max width $max_height = 150; // set a max height if($imgW > $imgH){ // width is greater // resize to width up to max if($imgW > $max_width) $image-

修复IE 6 PNG图片透明

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1.用ps制作一张宽度，高度都为1px的透明图片，保存到images/blank.gif 2.用记事本创建一个文件命名为iepngfix.htc，代码如下： <public:component> <public:attach event="onpropertychange" onevent="iePNGFix(0)" /> <script type="text/javascript"> // IE5.5+ PNG Alpha Fix v1.0 // (c) 2004-2008 Angus Turnbull http://www.twinhelix.com // This is licensed under the GNU LGPL, version 2.1 or later. // For details, see: http://creativecommons.org/licenses/LGPL/2.1/ // This must be a path to a blank image, relative to the HTML document(s). // In production use I suggest 'images/blank.gif' or similar. That's all! if (typeof blankImg == 'undefined') var

简单易懂的轮播图#

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简单易懂的轮播图# 首先建立一个img文件夹==添加你想要轮播的图图====注意图的名字为0.PNG，1.PNG，2.PNG ,3 .PNG(图片后缀可以为jpg,jpge等)然后开码码<img src="img/0.PNG" alt=""><script type="text/javascript"> var img=document.getElementsByTagName("img")[0]; var time=null var num=0; function lb(){ if (num==3){ num==-1 } num++ img.setAttribute("src","img/ "+num+".PNG") } time=setInterval("lb()",1000)</script></body>ok 点赞收藏分享文章举报鲸弋发布了1 篇原创文章 · 获赞 0 · 访问量 2 私信关注来源： CSDN 作者：鲸弋链接： https://blog.csdn.net/weixin_43469637/article/details/103712957

vue和react的区别之我见

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https://www.jianshu.com/p/b7cd52868e95?from=groupmessage vue和react的区别之我见凌霄光关注 92018.08.26 13:19:46字数 948阅读 89,015 react和vue都是做组件化的，整体的功能都类似，但是他们的设计思路是有很多不同的。使用react和vue，主要是理解他们的设计思路的不同。 1.数据是不是可变的 react整体是函数式的思想，把组件设计成纯组件，状态和逻辑通过参数传入，所以在react中，是单向数据流，推崇结合immutable来实现数据不可变。react在setState之后会重新走渲染的流程，如果shouldComponentUpdate返回的是true，就继续渲染，如果返回了false，就不会重新渲染，PureComponent就是重写了shouldComponentUpdate，然后在里面作了props和state的浅层对比。 image.png 而vue的思想是响应式的，也就是基于是数据可变的，通过对每一个属性建立Watcher来监听，当属性变化的时候，响应式的更新对应的虚拟dom。 image.png 总之，react的性能优化需要手动去做，而vue的性能优化是自动的，但是vue的响应式机制也有问题，就是当state特别多的时候，Watcher也会很多，会导致卡顿