add onStyleImageMissing to allow dynamically loaded or generated images (#14253)

Also make `Style#updateImage(...)` much faster when the image doesn't change size. This can be useful for asynchronously generating images.

2 files changed, 19 insertions, 0 deletions

diff --git a/src/mbgl/gl/context.cpp b/src/mbgl/gl/context.cpp
index 5ce035f691..6cee364379 100644
--- a/src/mbgl/gl/context.cpp
+++ b/src/mbgl/gl/context.cpp
@@ -546,6 +546,24 @@ void Context::updateTextureResource(const gfx::TextureResource& resource,
                                   Enum<gfx::TextureChannelDataType>::to(type), data));
 }
 
+void Context::updateTextureResourceSub(const gfx::TextureResource& resource,
+                                    const uint16_t xOffset,
+                                    const uint16_t yOffset,
+                                    const Size size,
+                                    const void* data,
+                                    gfx::TexturePixelType format,
+                                    gfx::TextureChannelDataType type) {
+    // Always use texture unit 0 for manipulating it.
+    activeTextureUnit = 0;
+    texture[0] = static_cast<const gl::TextureResource&>(resource).texture;
+    MBGL_CHECK_ERROR(glTexSubImage2D(GL_TEXTURE_2D, 0,
+                                  xOffset, yOffset,
+                                  size.width, size.height,
+                                  Enum<gfx::TexturePixelType>::to(format),
+                                  Enum<gfx::TextureChannelDataType>::to(type), data));
+}
+
+
 std::unique_ptr<gfx::DrawScopeResource> Context::createDrawScopeResource() {
     return std::make_unique<gl::DrawScopeResource>(createVertexArray());
 }
diff --git a/src/mbgl/gl/context.hpp b/src/mbgl/gl/context.hpp
index a4e6184ddb..d46727cb7a 100644
--- a/src/mbgl/gl/context.hpp
+++ b/src/mbgl/gl/context.hpp
@@ -211,6 +211,7 @@ private:
 
     std::unique_ptr<gfx::TextureResource> createTextureResource(Size, const void* data, gfx::TexturePixelType, gfx::TextureChannelDataType) override;
     void updateTextureResource(const gfx::TextureResource&, Size, const void* data, gfx::TexturePixelType, gfx::TextureChannelDataType) override;
+    void updateTextureResourceSub(const gfx::TextureResource&, const uint16_t xOffset, const uint16_t yOffset, Size, const void* data, gfx::TexturePixelType, gfx::TextureChannelDataType) override;
 
     std::unique_ptr<gfx::DrawScopeResource> createDrawScopeResource() override;