DebugTools: expect more differences in renderer tests on ARM Mali.

This makes the tests pass 100%.

src/Magnum/DebugTools/Test/ForceRendererGLTest.cpp

@@ -23,6 +23,7 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+#include <Corrade/Containers/Optional.h>
 #include <Corrade/PluginManager/Manager.h>
 #include <Corrade/Utility/Directory.h>
 
@@ -43,6 +44,10 @@
 
 #include "configure.h"
 
+#ifdef CORRADE_TARGET_ANDROID
+#include "Magnum/GL/Context.h"
+#endif
+
 namespace Magnum { namespace DebugTools { namespace Test { namespace {
 
 struct ForceRendererGLTest: GL::OpenGLTester {
@@ -107,10 +112,20 @@ void ForceRendererGLTest::render2D() {
        !(_manager.loadState("TgaImporter") & PluginManager::LoadState::Loaded))
         CORRADE_SKIP("AnyImageImporter / TgaImageImporter plugins not found.");
 
+    /* ARM Mali G71 (Huawei P10) has some rounding differences causing the
+       the arrowhead to be on a different place (but the rest is okay and the
+       3D case matches exactly), however to avoid false negatives elsewhere I'm
+       making it conditional. */
+    Containers::Optional<CompareImageToFile> comparator{Containers::InPlaceInit, _manager};
+    #ifdef CORRADE_TARGET_ANDROID
+    if(GL::Context::current().detectedDriver() & GL::Context::DetectedDriver::ArmMali)
+        comparator.emplace(_manager, 79.0f, 0.22f);
+    #endif
+
     CORRADE_COMPARE_WITH(
         framebuffer.read({{}, {64, 64}}, {PixelFormat::RGBA8Unorm}),
         Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "ForceRenderer2D.tga"),
-        CompareImageToFile{_manager});
+        *comparator);
 }
 
 void ForceRendererGLTest::render3D() {

src/Magnum/DebugTools/Test/ObjectRendererGLTest.cpp

@@ -23,6 +23,7 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+#include <Corrade/Containers/Optional.h>
 #include <Corrade/PluginManager/Manager.h>
 #include <Corrade/Utility/Directory.h>
 
@@ -43,6 +44,10 @@
 
 #include "configure.h"
 
+#ifdef CORRADE_TARGET_ANDROID
+#include "Magnum/GL/Context.h"
+#endif
+
 namespace Magnum { namespace DebugTools { namespace Test { namespace {
 
 struct ObjectRendererGLTest: GL::OpenGLTester {
@@ -153,11 +158,21 @@ void ObjectRendererGLTest::render3D() {
        !(_manager.loadState("TgaImporter") & PluginManager::LoadState::Loaded))
         CORRADE_SKIP("AnyImageImporter / TgaImporter plugins not found.");
 
+    /* Intel Windows drivers misplace one pixel here. Nothing serious.
+       ARM Mali G71 (Huawei P10) has some rounding differences causing the
+       the bottom blue line to be on a different place (but the rest is
+       okay and the 2D case matches exactly), however to avoid false negatives
+       elsewhere I'm making it conditional. */
+    Containers::Optional<CompareImageToFile> comparator{Containers::InPlaceInit, _manager,  71.6f, 0.018f};
+    #ifdef CORRADE_TARGET_ANDROID
+    if(GL::Context::current().detectedDriver() & GL::Context::DetectedDriver::ArmMali)
+        comparator.emplace(_manager, 127.6f, 0.54f);
+    #endif
+
     CORRADE_COMPARE_WITH(
         framebuffer.read({{}, {64, 64}}, {PixelFormat::RGBA8Unorm}),
         Utility::Directory::join(DEBUGTOOLS_TEST_DIR, "ObjectRenderer3D.tga"),
-        /* Intel Windows drivers misplace one pixel here. Nothing serious. */
+        *comparator);
-        (CompareImageToFile{_manager, 71.6f, 0.018f}));
 }
 
 }}}}