mdn / mdn/browser-compat-data

api.CanvasRenderingContext2D.globalAlpha - Doesn't work after safari 16.x and also 17.x version

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browser:safari data:api
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Description

What type of issue is this?

Browser bug (a bug with a feature that may impact site compatibility)

What information was incorrect, unhelpful, or incomplete?
<style> #canvas { border: 1px solid black; } </style>
<script>
    
    const canvas = document.getElementById("canvas");
    const ctx = canvas.getContext("2d");

    
    ctx.fillStyle = "red";
    ctx.fillRect(50, 50, 200, 200);

    
    ctx.globalCompositeOperation = "destination-in";
	ctx.fillRect(50, 50, 200, 200);
    ctx.globalAlpha = 0.5;
    // 绘制目标形状(圆形)
    ctx.fillStyle = "blue";
    ctx.beginPath();
    ctx.arc(200, 200, 100, 0, Math.PI * 2);
    ctx.closePath();
    ctx.fill();
</script>
What browsers does this problem apply to, if applicable?

Safari

What did you expect to see?

The transparency of image doesn't work on safari

Did you test this? If so, how?

Yes, deployed my code and show it on safari

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

No response

Do you have anything more you want to share?

I am not sure exact safari version.

MDN URL

https://developer.mozilla.org/zh-CN/docs/Web/API/CanvasRenderingContext2D/globalAlpha

MDN metadata
MDN page report details
  • Query: api.CanvasRenderingContext2D.globalAlpha
  • Report started: 2024-03-15T03:49:59.009Z

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the MDN CanvasRenderingContext2D.globalAlpha page and reproduce the supplied HTML/JavaScript canvas example in Safari 16.x and 17.x. Done means confirming the affected Safari versions and the observed compatibility behavior so the browser-compatibility data can be assessed.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
frontend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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