SDL: render: Clip lines before Bresenham algorithm generates points.

From 983f178b7d3ebf002ef3ec3cdf73f93766bfccd0 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Fri, 24 Nov 2023 19:31:30 -0500
Subject: [PATCH] render: Clip lines before Bresenham algorithm generates
 points.

Otherwise, a massive line might generate gigabytes worth of points to render,
which the backend would simply throw away anyhow.

Fixes #8113.

(cherry picked from commit 4339647d900bb8559ac3f6258166d21fe6d72a9a)
---
 src/render/SDL_render.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
index 533a2fe524c5..e7006fb407b1 100644
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -2755,6 +2755,18 @@ static int RenderLineBresenham(SDL_Renderer *renderer, int x1, int y1, int x2, i
     int retval;
     SDL_bool isstack;
     SDL_FPoint *points;
+    SDL_Rect clip_rect;
+
+    /* the backend might clip this further to the clipping rect, but we
+       just want a basic safety against generating millions of points for
+       massive lines. */
+    clip_rect.x = (int) renderer->viewport.x;
+    clip_rect.y = (int) renderer->viewport.y;
+    clip_rect.w = (int) renderer->viewport.w;
+    clip_rect.h = (int) renderer->viewport.h;
+    if (!SDL_IntersectRectAndLine(&clip_rect, &x1, &y1, &x2, &y2)) {
+        return 0;
+    }
 
     deltax = SDL_abs(x2 - x1);
     deltay = SDL_abs(y2 - y1);