Merge lp:~widelands-dev/widelands/bug-1818494-workaround-math-clamp-zoom-everywhere into lp:widelands

[GunChleoc]

Use math::clamp to ensure that zoom will stay within range.

I'm no sure whether this actually fixes or only masks the bug. We might only want this in the Build 20 branch, hoping that it will prevent crashes there.

[bunnybot (widelandsofficial)]

Continuous integration builds have changed state:

Travis build 4661. State: passed. Details: https://travis-ci.org/widelands/widelands/builds/513789175.
Appveyor build 4448. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_widelands_dev_widelands_bug_1818494_workaround_math_clamp_zoom_everywhere-4448.

[GunChleoc (gunchleoc)]

We now have a protocol in the bug and it looks like this fix is OK, so let's have it in trunk ASAP.

[hessenfarmer (stephan-lutz)]

I just tested the branch and did some Zooming moving around using the minimap to change view.

No anomalies. But I wasn't able to reproduce the original bug in older branches so no idea if this is fixed. At least it should be safe to go.

review: Approve (test)

[GunChleoc (gunchleoc)]

Let's have it then and hope that it will fix it.

@bunnybot merge

[hessenfarmer (stephan-lutz)]

As I interpret the latest log from HHKing unfortunately it is not fixed yet

[GunChleoc (gunchleoc)]

No, it's not :'(

I have pushed another attempt for him to fix to the logging branch and have created a new one, but I will hold off with further merge requests until we hear back from him.

=== modified file 'src/wui/mapview.cc'
--- src/wui/mapview.cc	2019-03-25 10:46:23 +0000
+++ src/wui/mapview.cc	2019-03-31 15:40:28 +0000
@@ -123,7 +123,8 @@
                             std::deque<MapView::TimestampedView>* plan) {
 	for (int i = 1; i < kNumKeyFrames - 2; i++) {
 		float dt = (duration_ms / kNumKeyFrames) * i;
-		const float zoom = zoom_t.value(dt);
+		// Using math::clamp as a workaround for https://bugs.launchpad.net/widelands/+bug/1818494
+		const float zoom = math::clamp(zoom_t.value(dt), 1.f / kMaxZoom, kMaxZoom);
 		const Vector2f center_point = center_point_t.value(dt);
 		const Vector2f viewpoint = center_point - Vector2f(width * zoom / 2.f, height * zoom / 2.f);
 		plan->push_back(MapView::TimestampedView{
@@ -392,6 +393,8 @@
 			return;
 		}
 		view_ = target_view;
+		// Using math::clamp as a workaround for https://bugs.launchpad.net/widelands/+bug/1818494
+		view_.zoom = math::clamp(view_.zoom, 1.f / kMaxZoom, kMaxZoom);
 		MapviewPixelFunctions::normalize_pix(map_, &view_.viewpoint);
 		changeview();
 		return;