Fix Vulkan headless backend resize (#4030)

include/mbgl/mtl/texture2d.hpp

@@ -66,6 +66,7 @@ public:
 private:
     MTL::PixelFormat getMetalPixelFormat() const noexcept;
     void createMetalTexture() noexcept;
+    void destroyMetalTexture() noexcept;
 
     Context& context;
     MTLTexturePtr metalTexture;

platform/default/src/mbgl/vulkan/headless_backend.cpp

@@ -75,16 +75,21 @@ gfx::Renderable& HeadlessBackend::getDefaultRenderable() {
 }
 
 PremultipliedImage HeadlessBackend::readStillImage() {
+    if (!resource) {
+        resource = std::make_unique<HeadlessRenderableResource>(*this);
+    }
+
     auto& contextImpl = static_cast<Context&>(*context);
     auto& resourceImpl = static_cast<HeadlessRenderableResource&>(*resource);
 
     if (!texture) {
         texture = std::make_unique<Texture2D>(contextImpl);
         texture->setFormat(gfx::TexturePixelType::RGBA, gfx::TextureChannelDataType::UnsignedByte);
-        texture->setSize(size);
         texture->setUsage(Texture2DUsage::Read);
     }
 
+    texture->setSize(size);
+
     contextImpl.waitFrame();
     texture->copyImage(resourceImpl.getAcquiredImage());
 

src/mbgl/mtl/texture2d.cpp

@@ -14,10 +14,7 @@ Texture2D::Texture2D(Context& context_)
     : context(context_) {}
 
 Texture2D::~Texture2D() {
-    if (metalTexture) {
-        context.renderingStats().numActiveTextures--;
-        context.renderingStats().memTextures -= getDataSize(); // NOLINT(clang-analyzer-optin.cplusplus.VirtualCall)
-    }
+    destroyMetalTexture();
 }
 
 gfx::Texture2D& Texture2D::setSamplerConfiguration(const SamplerState& samplerState_) noexcept {
@@ -36,6 +33,9 @@ gfx::Texture2D& Texture2D::setFormat(gfx::TexturePixelType pixelFormat_,
     if (pixelFormat_ == pixelFormat && channelType_ == channelType) {
         return *this;
     }
+
+    destroyMetalTexture();
+
     pixelFormat = pixelFormat_;
     channelType = channelType_;
     textureDirty = true;
@@ -46,6 +46,9 @@ gfx::Texture2D& Texture2D::setSize(mbgl::Size size_) noexcept {
     if (size_ == size) {
         return *this;
     }
+
+    destroyMetalTexture();
+
     size = size_;
     textureDirty = true;
     return *this;
@@ -146,7 +149,8 @@ void Texture2D::createMetalTexture() noexcept {
     if (size == Size{0, 0}) {
         return;
     }
-    metalTexture.reset();
+
+    destroyMetalTexture();
 
     const auto format = getMetalPixelFormat();
     if (format == MTL::PixelFormat::PixelFormatInvalid) {
@@ -195,6 +199,16 @@ void Texture2D::create() noexcept {
     }
 }
 
+void Texture2D::destroyMetalTexture() noexcept {
+    if (!metalTexture) {
+        return;
+    }
+
+    metalTexture.reset();
+    context.renderingStats().numActiveTextures--;
+    context.renderingStats().memTextures -= getDataSize();
+}
+
 gfx::Texture2D& Texture2D::setUsage(MTL::TextureUsage usage_) noexcept {
     usage = usage_;
     textureDirty = true;

src/mbgl/vulkan/texture2d.cpp

@@ -62,6 +62,9 @@ gfx::Texture2D& Texture2D::setFormat(gfx::TexturePixelType pixelFormat_,
     if (pixelFormat_ == pixelFormat && channelType_ == channelType) {
         return *this;
     }
+
+    destroyTexture();
+
     pixelFormat = pixelFormat_;
     channelType = channelType_;
     textureDirty = true;
@@ -72,6 +75,9 @@ gfx::Texture2D& Texture2D::setSize(mbgl::Size size_) noexcept {
     if (size_ == size) {
         return *this;
     }
+
+    destroyTexture();
+
     size = size_;
     textureDirty = true;
     return *this;
@@ -267,6 +273,8 @@ vk::SamplerAddressMode Texture2D::vulkanAddressMode(const gfx::TextureWrapType t
 void Texture2D::createTexture() {
     if (size.width == 0 || size.height == 0) return;
 
+    destroyTexture();
+
     const auto& backend = context.getBackend();
 
     const auto format = vulkanFormat(pixelFormat, channelType);