Merge lp:~vanvugt/mir/black-bars into lp:mir

[Daniel van Vugt]

Add letterboxing/black bars support to the GL renderer, for when
the logical viewport aspect doesn't match that of the screen.

This will be used in future for arbitrary cloning of one monitor
to another (LP: #1639226)

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:4038
https://mir-jenkins.ubuntu.com/job/mir-ci/2997/
Executed test runs:
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-mir/3994
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-0-fetch/4080
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=vivid+overlay/4070
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=xenial+overlay/4070
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-1-sourcepkg/release=zesty/4070
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=clang,platform=mesa,release=zesty/4021/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=xenial+overlay/4021/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=amd64,compiler=gcc,platform=mesa,release=zesty/4021/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=cross-armhf,compiler=gcc,platform=android,release=vivid+overlay/4021/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=android,release=vivid+overlay/4021/artifact/output/*zip*/output.zip
    SUCCESS: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4021
        deb: https://mir-jenkins.ubuntu.com/job/build-2-binpkg-mir/arch=i386,compiler=gcc,platform=mesa,release=xenial+overlay/4021/artifact/output/*zip*/output.zip

Click here to trigger a rebuild:
https://mir-jenkins.ubuntu.com/job/mir-ci/2997/rebuild

review: Approve (continuous-integration)

[Brandon Schaefer (brandontschaefer)]

lgtm

review: Approve

=== modified file 'src/renderers/gl/renderer.cpp'
--- src/renderers/gl/renderer.cpp	2017-01-27 08:13:36 +0000
+++ src/renderers/gl/renderer.cpp	2017-02-15 10:20:35 +0000
@@ -370,6 +370,37 @@
                       0.0f});
 
     viewport = rect;
+
+    /*
+     * Letterboxing: Move the glViewport to add black bars in the case that
+     * the logical viewport aspect ratio doesn't match the display aspect.
+     * This keeps pixels square. Note "black"-bars are really glClearColor.
+     */
+    auto transformed_viewport = display_transform *
+                                glm::vec4(viewport.size.width.as_int(),
+                                          viewport.size.height.as_int(), 0, 1);
+    auto viewport_width = fabs(transformed_viewport[0]);
+    auto viewport_height = fabs(transformed_viewport[1]);
+    auto dpy = eglGetCurrentDisplay();
+    auto surf = eglGetCurrentSurface(EGL_DRAW);
+    EGLint buf_width = 0, buf_height = 0;
+
+    if (viewport_width > 0.0f && viewport_height > 0.0f &&
+        eglQuerySurface(dpy, surf, EGL_WIDTH, &buf_width) && buf_width > 0 &&
+        eglQuerySurface(dpy, surf, EGL_HEIGHT, &buf_height) && buf_height > 0)
+    {
+        GLint reduced_width = buf_width, reduced_height = buf_height;
+        // if viewport_aspect_ratio >= buf_aspect_ratio
+        if (viewport_width * buf_height >= buf_width * viewport_height)
+            reduced_height = buf_width * viewport_height / viewport_width;
+        else
+            reduced_width = buf_height * viewport_width / viewport_height;
+
+        GLint offset_x = (buf_width - reduced_width) / 2;
+        GLint offset_y = (buf_height - reduced_height) / 2;
+
+        glViewport(offset_x, offset_y, reduced_width, reduced_height);
+    }
 }
 
 void mrg::Renderer::set_output_transform(glm::mat2 const& t)

=== modified file 'tests/unit-tests/renderers/gl/test_gl_renderer.cpp'
--- tests/unit-tests/renderers/gl/test_gl_renderer.cpp	2016-01-29 08:18:22 +0000
+++ tests/unit-tests/renderers/gl/test_gl_renderer.cpp	2017-02-15 10:20:35 +0000
@@ -39,6 +39,7 @@
 using testing::Pointee;
 using testing::AnyNumber;
 using testing::AtLeast;
+using testing::DoAll;
 using testing::_;
 
 namespace mt=mir::test;
@@ -314,3 +315,103 @@
 
     renderer.render(renderable_list);
 }
+
+TEST_F(GLRenderer, sets_viewport_unscaled_exact)
+{
+    int const screen_width = 1920;
+    int const screen_height = 1080;
+    mir::geometry::Rectangle const view_area{{0,0}, {1920,1080}};
+
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_WIDTH,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_width),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_HEIGHT,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_height),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_display_buffer, view_area())
+        .WillByDefault(Return(view_area));
+
+    EXPECT_CALL(mock_gl, glViewport(0, 0, screen_width, screen_height));
+
+    mrg::Renderer renderer(mock_display_buffer);
+}
+
+TEST_F(GLRenderer, sets_viewport_upscaled_exact)
+{
+    int const screen_width = 1920;
+    int const screen_height = 1080;
+    mir::geometry::Rectangle const view_area{{0,0}, {1280,720}};
+
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_WIDTH,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_width),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_HEIGHT,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_height),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_display_buffer, view_area())
+        .WillByDefault(Return(view_area));
+
+    EXPECT_CALL(mock_gl, glViewport(0, 0, screen_width, screen_height));
+
+    mrg::Renderer renderer(mock_display_buffer);
+}
+
+TEST_F(GLRenderer, sets_viewport_downscaled_exact)
+{
+    int const screen_width = 1280;
+    int const screen_height = 720;
+    mir::geometry::Rectangle const view_area{{0,0}, {1920,1080}};
+
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_WIDTH,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_width),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_HEIGHT,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_height),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_display_buffer, view_area())
+        .WillByDefault(Return(view_area));
+
+    EXPECT_CALL(mock_gl, glViewport(0, 0, screen_width, screen_height));
+
+    mrg::Renderer renderer(mock_display_buffer);
+}
+
+TEST_F(GLRenderer, sets_viewport_upscaled_narrow)
+{
+    int const screen_width = 1920;
+    int const screen_height = 1080;
+    mir::geometry::Rectangle const view_area{{0,0}, {640,480}};
+
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_WIDTH,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_width),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_HEIGHT,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_height),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_display_buffer, view_area())
+        .WillByDefault(Return(view_area));
+
+    EXPECT_CALL(mock_gl, glViewport(240, 0, 1440, 1080));
+
+    mrg::Renderer renderer(mock_display_buffer);
+}
+
+TEST_F(GLRenderer, sets_viewport_downscaled_wide)
+{
+    int const screen_width = 640;
+    int const screen_height = 480;
+    mir::geometry::Rectangle const view_area{{0,0}, {1920,1080}};
+
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_WIDTH,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_width),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_egl, eglQuerySurface(_,_,EGL_HEIGHT,_))
+        .WillByDefault(DoAll(SetArgPointee<3>(screen_height),
+                             Return(EGL_TRUE)));
+    ON_CALL(mock_display_buffer, view_area())
+        .WillByDefault(Return(view_area));
+
+    EXPECT_CALL(mock_gl, glViewport(0, 60, 640, 360));
+
+    mrg::Renderer renderer(mock_display_buffer);
+}