[core] Fix image type of Map::renderStill

It's a premultiplied image. This implies that we were misusing encodePNG
in most cases, as we were passing premultiplied pixels which were then
interpreted as unmultiplied. I changed encodePNG to accept premultipled
pixels, and unpremultiply in the implementations.

3 files changed, 9 insertions, 9 deletions

diff --git a/test/api/annotations.cpp b/test/api/annotations.cpp
index c4fea02079..ae9c804730 100644
--- a/test/api/annotations.cpp
+++ b/test/api/annotations.cpp
@@ -14,16 +14,16 @@
 
 using namespace mbgl;
 
-UnassociatedImage render(Map& map) {
-    std::promise<UnassociatedImage> promise;
-    map.renderStill([&](std::exception_ptr, UnassociatedImage&& image) {
+PremultipliedImage render(Map& map) {
+    std::promise<PremultipliedImage> promise;
+    map.renderStill([&](std::exception_ptr, PremultipliedImage&& image) {
         promise.set_value(std::move(image));
     });
     return std::move(promise.get_future().get());
 }
 
 void checkRendering(Map& map, const char * name) {
-    UnassociatedImage actual = render(map);
+    PremultipliedImage actual = render(map);
     test::checkImage(std::string("test/fixtures/annotations/") + name + "/",
                      actual, 0.0002, 0.1);
 }
diff --git a/test/api/api_misuse.cpp b/test/api/api_misuse.cpp
index 4d5fe11042..538f09a040 100644
--- a/test/api/api_misuse.cpp
+++ b/test/api/api_misuse.cpp
@@ -45,7 +45,7 @@ TEST(API, RenderWithoutStyle) {
     Map map(view, fileSource, MapMode::Still);
 
     std::promise<std::exception_ptr> promise;
-    map.renderStill([&promise](std::exception_ptr error, UnassociatedImage&&) {
+    map.renderStill([&promise](std::exception_ptr error, PremultipliedImage&&) {
         promise.set_value(error);
     });
 
diff --git a/test/api/repeated_render.cpp b/test/api/repeated_render.cpp
index 79349c67e7..77e4569dbf 100644
--- a/test/api/repeated_render.cpp
+++ b/test/api/repeated_render.cpp
@@ -25,8 +25,8 @@ TEST(API, RepeatedRender) {
 
     {
         map.setStyleJSON(style, "");
-        std::promise<UnassociatedImage> promise;
-        map.renderStill([&promise](std::exception_ptr, UnassociatedImage&& image) {
+        std::promise<PremultipliedImage> promise;
+        map.renderStill([&promise](std::exception_ptr, PremultipliedImage&& image) {
             promise.set_value(std::move(image));
         });
         auto result = std::move(promise.get_future().get());
@@ -37,8 +37,8 @@ TEST(API, RepeatedRender) {
 
     {
         map.setStyleJSON(style, "TEST_DATA/suite");
-        std::promise<UnassociatedImage> promise;
-        map.renderStill([&promise](std::exception_ptr, UnassociatedImage&& image) {
+        std::promise<PremultipliedImage> promise;
+        map.renderStill([&promise](std::exception_ptr, PremultipliedImage&& image) {
             promise.set_value(std::move(image));
         });
         auto result = std::move(promise.get_future().get());