The benchmark tests the performance of two different methods for rendering images onto a canvas in HTML5: drawImage and putImageData. These methods differ in how they handle the image data being drawn, and the benchmark compares their performance when working with a base image drawn on a master canvas.

Benchmark Comparison

1. DrawImage Method:

   • Test Cases:

     • "DrawImage whole master into di canvas"
       • Definition: di.drawImage(master, 0, 0);
     • "DrawImage half master into di canvas"
       • Definition: di.drawImage(master, 25, 0, 50, 100, 25, 0, 50, 100);

   • Description: The drawImage function is a more straightforward method to copy an image or a part of an image from one canvas to another. In this benchmark, it tests both the full image from the master canvas and a subsection of the image.

   • Pros:

     • Simplicity in usage—just a single call.
     • Handles scaling and cropping inherently based on parameters.
     • Can be faster for direct copying of images.

   • Cons:

     • More overhead involved if you are extracting and manipulating pixel data extensively.

2. PutImageData Method:

   • Test Cases:

     • "PutImageData whole master into pid canvas"
       • Definition: pid.putImageData(imgData1, 0, 0);
     • "PutImageData half master into pid canvas"
       • Definition: pid.putImageData(imgData2, 25, 0);

   • Description: putImageData is used to draw a rectangular area of pixel data onto the canvas. In this benchmark, it takes extracted pixel image data from the master canvas and puts it into a second canvas.

   • Pros:

     • Provides more control over individual pixel manipulation if needed.
     • Allows drawing image data that may have been altered after extraction.

   • Cons:

     • Generally slower than drawImage for straightforward image copying tasks due to additional overhead of handling pixel data directly.
     • More complex to use if only copying images.

Performance Results Overview

The benchmark results reveal the executions per second for each of the test cases performed in Chrome 133 on a Windows Desktop environment:

• The fastest test case is drawing a half image using drawImage, resulting in approximately 603,849 executions per second.
• The second-best performing action is drawing the whole image using drawImage, achieving 590,539 executions per second.
• Both putImageData calls (both full and half images) performed significantly slower, with the fastest being around 57,760 executions per second for the half image and only 53,754 for the full image.

Other Considerations and Alternatives

When deciding between drawImage and putImageData, developers may also consider the following:

• Use Cases: If direct and straightforward image copying is needed, drawImage is typically preferred. However, if there's a requirement for direct pixel manipulation or performance enhancements through preprocessing of pixel data, putImageData is a better choice.
• Browser Support: Both methods are widely supported across modern browsers.

Summary

In summary, this benchmark explores the performance trade-offs between using drawImage, which is generally faster and easier for copying images, and putImageData, which offers more granular control over pixel manipulation but comes with a performance penalty. Depending on the specific requirements of a project, developers can choose the most suitable approach based on these performance characteristics and their specific use case.