HTML5 Canvas Size: CSS or Attributes – Which Method Ensures Accurate Drawing?

Size Discrepancy in HTML5 Canvas: CSS vs Attributes

In the creation of HTML5 canvases, one may encounter varying results when setting size attributes directly or using Cascading Style Sheets (CSS). Consider the following code snippets:

This CSS-driven approach scales the canvas when zoomed. In contrast, setting the attributes directly produces the expected result:

To explain this discrepancy, it's important to understand the distinct roles of these two elements:

• Canvas Element Attributes (width, height): These attributes specify the actual size of the canvas in pixels, allowing for drawing within those dimensions. If unspecified, the default resolution is 300px by 150px, as per HTML5 specifications.
• CSS Properties (width, height): These properties determine the size at which the canvas element displays on screen. If not set, the intrinsic размер of the element (determined by the attributes) influences its layout.

When CSS dimensions differ from the actual canvas dimensions, the browser must scale the canvas to fit the desired display size. This can result in distortion if the aspect ratio is not maintained. A live example of this behavior is available here: http://jsfiddle.net/9bheb/5/.

Therefore, it's crucial to carefully consider the desired outcome when setting canvas sizes. For accurate and undistorted drawing, it's recommended to specify the dimensions directly using the canvas element attributes rather than relying solely on CSS properties.

The above is the detailed content of HTML5 Canvas Size: CSS or Attributes – Which Method Ensures Accurate Drawing?. For more information, please follow other related articles on the PHP Chinese website!