wasm: move image to web conversion to dom::

This allows other areas to utilize this

Change-Id: I4bc7e8374289a19afe8b639b2b3b0dc0f8f65a3a
Done-with: Mikolaj.Boc@qt.io
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/wasm/qwasmbackingstore.cpp

@@ -4,6 +4,7 @@
 #include "qwasmbackingstore.h"
 #include "qwasmwindow.h"
 #include "qwasmcompositor.h"
+#include "qwasmdom.h"
 
 #include <QtGui/qpainter.h>
 #include <QtGui/qbackingstore.h>
@@ -75,39 +76,8 @@ void QWasmBackingStore::updateTexture(QWasmWindow *window)
         clippedDpiScaledRegion |= r;
     }
 
-    for (const QRect &dirtyRect : clippedDpiScaledRegion) {
+    for (const QRect &dirtyRect : clippedDpiScaledRegion)
-        constexpr int BytesPerColor = 4;
+        dom::drawImageToWebImageDataArray(m_image, m_webImageDataArray, dirtyRect);
-        if (dirtyRect.width() == imageRect.width()) {
-            // Copy a contiguous chunk of memory
-            // ...............
-            // OOOOOOOOOOOOOOO
-            // OOOOOOOOOOOOOOO -> image data
-            // OOOOOOOOOOOOOOO
-            // ...............
-            auto imageMemory = emscripten::typed_memory_view(dirtyRect.width() * dirtyRect.height()
-                                                                     * BytesPerColor,
-                                                             m_image.constScanLine(dirtyRect.y()));
-            m_webImageDataArray["data"].call<void>("set", imageMemory,
-                                                   dirtyRect.y() * m_image.width() * BytesPerColor);
-        } else {
-            // Go through the scanlines manually to set the individual lines in bulk. This is
-            // marginally less performant than the above.
-            // ...............
-            // ...OOOOOOOOO... r = 0  -> image data
-            // ...OOOOOOOOO... r = 1  -> image data
-            // ...OOOOOOOOO... r = 2  -> image data
-            // ...............
-            for (int r = 0; r < dirtyRect.height(); ++r) {
-                auto scanlineMemory = emscripten::typed_memory_view(
-                        dirtyRect.width() * BytesPerColor,
-                        m_image.constScanLine(r + dirtyRect.y()) + BytesPerColor * dirtyRect.x());
-                m_webImageDataArray["data"].call<void>("set", scanlineMemory,
-                                                       (dirtyRect.y() + r) * m_image.width()
-                                                                       * BytesPerColor
-                                                               + dirtyRect.x() * BytesPerColor);
-            }
-        }
-    }
 
     m_dirty = QRegion();
 }

src/plugins/platforms/wasm/qwasmdom.cpp

@@ -36,6 +36,46 @@ QPointF mapPoint(emscripten::val source, emscripten::val target, const QPointF &
     return point + offset;
 }
 
+void drawImageToWebImageDataArray(const QImage &sourceImage, emscripten::val destinationImageData,
+                                  const QRect &sourceRect)
+{
+    Q_ASSERT_X(destinationImageData["constructor"]["name"].as<std::string>() == "ImageData",
+               Q_FUNC_INFO, "The destination should be an ImageData instance");
+
+    constexpr int BytesPerColor = 4;
+    if (sourceRect.width() == sourceImage.width()) {
+        // Copy a contiguous chunk of memory
+        // ...............
+        // OOOOOOOOOOOOOOO
+        // OOOOOOOOOOOOOOO -> image data
+        // OOOOOOOOOOOOOOO
+        // ...............
+        auto imageMemory = emscripten::typed_memory_view(sourceRect.width() * sourceRect.height()
+                                                                 * BytesPerColor,
+                                                         sourceImage.constScanLine(sourceRect.y()));
+        destinationImageData["data"].call<void>(
+                "set", imageMemory, sourceRect.y() * sourceImage.width() * BytesPerColor);
+    } else {
+        // Go through the scanlines manually to set the individual lines in bulk. This is
+        // marginally less performant than the above.
+        // ...............
+        // ...OOOOOOOOO... r = 0  -> image data
+        // ...OOOOOOOOO... r = 1  -> image data
+        // ...OOOOOOOOO... r = 2  -> image data
+        // ...............
+        for (int row = 0; row < sourceRect.height(); ++row) {
+            auto scanlineMemory =
+                    emscripten::typed_memory_view(sourceRect.width() * BytesPerColor,
+                                                  sourceImage.constScanLine(row + sourceRect.y())
+                                                          + BytesPerColor * sourceRect.x());
+            destinationImageData["data"].call<void>("set", scanlineMemory,
+                                                    (sourceRect.y() + row) * sourceImage.width()
+                                                                    * BytesPerColor
+                                                            + sourceRect.x() * BytesPerColor);
+        }
+    }
+}
+
 } // namespace dom
 
 QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmdom.h

@@ -16,6 +16,7 @@
 QT_BEGIN_NAMESPACE
 
 class QPoint;
+class QRect;
 
 namespace dom {
 inline emscripten::val document()
@@ -26,6 +27,9 @@ inline emscripten::val document()
 void syncCSSClassWith(emscripten::val element, std::string cssClassName, bool flag);
 
 QPointF mapPoint(emscripten::val source, emscripten::val target, const QPointF &point);
+
+void drawImageToWebImageDataArray(const QImage &source, emscripten::val destinationImageData,
+                                  const QRect &sourceRect);
 } // namespace dom
 
 QT_END_NAMESPACE