[wesnoth-commits] [wesnoth/wesnoth] 3bf153: Do not use SDL render API for certain drawing oper...

[Charles Dang]

  Branch: refs/heads/master
  Home:   https://github.com/wesnoth/wesnoth
  Commit: 3bf1530481fce7421a90f2b0dd525dc767ccb76e
      https://github.com/wesnoth/wesnoth/commit/3bf1530481fce7421a90f2b0dd525dc767ccb76e
  Author: Iris Morelle <shadowm at wesnoth.org>
  Date:   2020-01-13 (Mon, 13 Jan 2020)

  Changed paths:
    M src/display.cpp
    M src/help/help_text_area.cpp

  Log Message:
  -----------
  Do not use SDL render API for certain drawing operations

With the introduction of batched rendering in SDL 2.0.10, the behaviour
of the render API appears to have changed so that certain operations
forcibly queue a renderer clip rectangle set operation, using a default
rectangle if necessary. The command queue does not clean after itself
since it appears that the operating assumption is that you either use
the renderer API or you don't, and Wesnoth performs drawing operations
both with and without it in a few places.

With commit 4cbd6529e3d5f378d4dd0080dda8a47025b0d50d, our drawing
primitives were changed ("refactored") so that the render API is
forcibly used by them. When combined with contexts that use the
clip_rect_setter object, things get weird since the clipping rectangle
is reset behind the code's back.

As I see it, there's two solutions to this:

 1. Make clip_rect_setter use SDL_RenderSetClipRect(). The problem with
    this is that there are at least 3-4 places using clip_rect_setter on
    a target that isn't the screen framebuffer. Finding out whether the
    target surface *is* the screen seems like an inconvenient chore.

 2. Don't use the render API ever.

 3. Keep using the render API (a lot of other things do use it, such as
    the GUI2 canvas implementation) and change the few contexts where we
    use clip_rect_setter together with drawing primitives to call the
    SDL_Surface drawing primitives directly instead of using the render
    API.

This patch goes with option 3 since it seems the least intrusive. While
this fixes the two known cases of bug #4510 as of this writing (help
browser and minimap outline), I am not entirely sure if there are any
other users of clip_rect_setter hiding drawing primitive calls somewhere
underneath.

Also added relevant source comments in case someone decides to refactor
the involved code and break it again. It's especially necessary in the
minimap's case since we need to draw a grand total of 4 different
rectangles at once.

Fixes #4510.


  Commit: c239ae35d4f24430781f49840f9e0fc55ebe43b1
      https://github.com/wesnoth/wesnoth/commit/c239ae35d4f24430781f49840f9e0fc55ebe43b1
  Author: Charles Dang <exodia339 at gmail.com>
  Date:   2020-01-13 (Mon, 13 Jan 2020)

  Changed paths:
    M src/display.cpp
    M src/help/help_text_area.cpp

  Log Message:
  -----------
  Merge pull request #4704 from shikadiqueen/bug/4510

Do not use SDL render API for certain drawing operations


Compare: https://github.com/wesnoth/wesnoth/compare/f04ad5a3508f...c239ae35d4f2