Original GD's problem: Every image is read twice (at least for DSL)

[shenlebantongying]

DSL::nodeToHtml loads the image and then checks the image's size https://github.com/goldendict/goldendict/blob/1.5.0/dsl.cc#L915-L1003

DslResourceRequest::run sends the data to the browser https://github.com/goldendict/goldendict/blob/1.5.0/dsl.cc#L1912-L1955

Try this dict with single image test_dsl.zip

Set a breakpoint at File::loadFromFile, and you can see 2 calls reaches it.

Better solution: replace the size checking with CSS's image max-width.

[xiaoyifang]

Agree, use css to control the image size should be better

[xiaoyifang]

DSL::nodeToHtml loads the image and then checks the image's size https://github.com/goldendict/goldendict/blob/1.5.0/dsl.cc#L915-L1003

this whole logic can be removed . because there is no place to configure the maxPictureWidth, which lead the resize variable is always false.

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Which means all the logic about the save/restore of maxPictureWidth can be remove.

and the custom protocol gdpicture can be removed too.(can be in another PR)