jimp-dev/jimp

when rotate, the width and height of pic gets larger

Open

#808 创建于 2019年10月25日

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 (0 评论) (4 反应) (0 负责人)JavaScript (13,218 star) (785 fork)batch import
bughelp wanted

描述

When I call roatet serval on the same object, the width and height of pic gets larger. after call rotate about 10 times, the pic will have a quiet obvious black border.

The follwoing code:

Jimp.read('https://s3-us-west-2.amazonaws.com/s.cdpn.io/123941/koala.jpg', (error, lenna) => {
        if (error) throw error;
        lenna
          .rotate(90)
          .rotate(90)
          .rotate(90)
          .rotate(90)
          .rotate(90)
          .rotate(90)
          .rotate(90)
          .getBase64(Jimp.AUTO, (err, base64) => {
            this.imageRef.setAttribute('src', base64);
          });
      });

Expected Behavior

The pic rotate with the original width and height.

Current Behavior

the pic will have black border ,the width and height of pic will grow evey time.

Context

  • Jimp Version: ^0.8.5
  • Operating System: win10
  • Node version: v10.16.3

贡献者指南

技术栈
javascript
领域
backend
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
2
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
half day
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
JavaScriptJimp basics
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
70
研究方向
Investigate the `rotate` method in Jimp's source code (likely in the image manipulation module). The issue suggests that successive rotations increase the image dimensions instead of preserving them. Look for how the rotation is implemented, especially the calculation of output dimensions and any cropping logic. Check if each rotation accumulates the black border due to off center rotation or incorrect dimension handling. Consider adding a fix that ensures the output size remains constant when rotating by multiples of 90 degrees, or cropping to original dimensions after rotation.