From 790397ae0f05a8dfc8694c4d99197d5be2ccbce9 Mon Sep 17 00:00:00 2001
From: Victor Woeltjen <victor.woeltjen@nasa.gov>
Date: Mon, 9 Feb 2015 16:07:05 -0800
Subject: [PATCH 1/2] [Plot] Add test for buffer size

Add test case for usage of drawing buffer size as
reported by WebGL (instead of assuming we always got
the full size we requested.) WTD-852.
---
 platform/features/plot/test/GLChartSpec.js | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/platform/features/plot/test/GLChartSpec.js b/platform/features/plot/test/GLChartSpec.js
index cfd38d0638..67ec83aa73 100644
--- a/platform/features/plot/test/GLChartSpec.js
+++ b/platform/features/plot/test/GLChartSpec.js
@@ -106,6 +106,19 @@ define(
                 expect(mockGL.drawArrays)
                     .toHaveBeenCalledWith("TRIANGLE_FAN", 0, 4);
             });
+
+            it("uses buffer sizes reported by WebGL", function () {
+                // Make sure that GLChart uses the GL buffer size, which may
+                // differ from what canvas requested. WTD-852
+                mockCanvas.width = 300;
+                mockCanvas.height = 150;
+                mockGL.drawingBufferWidth = 200;
+                mockGL.drawingBufferHeight = 175;
+
+                glChart.clear();
+
+                expect(mockGL.viewport).toHaveBeenCalledWith(0, 0, 200, 175);
+            });
         });
     }
 );
\ No newline at end of file

From 7c5c96ff1ded33201a251e4666ec4597cb2bc63c Mon Sep 17 00:00:00 2001
From: Victor Woeltjen <victor.woeltjen@nasa.gov>
Date: Mon, 9 Feb 2015 16:10:20 -0800
Subject: [PATCH 2/2] [Plot] Use GL-reported buffer size

Use the buffer width/height reported by WebGL when
configuring the viewport to ensure that data aligns
correctly to canvas size when drawn. WTD-852.
---
 platform/features/plot/src/GLChart.js | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/platform/features/plot/src/GLChart.js b/platform/features/plot/src/GLChart.js
index 284333beaf..7dcda27a70 100644
--- a/platform/features/plot/src/GLChart.js
+++ b/platform/features/plot/src/GLChart.js
@@ -96,7 +96,15 @@ define(
                  * Clear the chart.
                  */
                 clear: function () {
-                    gl.viewport(0, 0, canvas.width, canvas.height);
+                    // Set the viewport size; note that we use the width/height
+                    // that our WebGL context reports, which may be lower
+                    // resolution than the canvas we requested.
+                    gl.viewport(
+                        0,
+                        0,
+                        gl.drawingBufferWidth,
+                        gl.drawingBufferHeight
+                    );
                     gl.clear(gl.COLOR_BUFFER_BIT + gl.DEPTH_BUFFER_BIT);
                 },
                 /**
@@ -107,8 +115,11 @@ define(
                  *        origin of the chart
                  */
                 setDimensions: function (dimensions, origin) {
-                    gl.uniform2fv(uDimensions, dimensions);
-                    gl.uniform2fv(uOrigin, origin);
+                    if (dimensions && dimensions.length > 0 &&
+                            origin && origin.length > 0) {
+                        gl.uniform2fv(uDimensions, dimensions);
+                        gl.uniform2fv(uOrigin, origin);
+                    }
                 },
                 /**
                  * Draw the supplied buffer as a line strip (a sequence