[graphics/krita/krita/6.0] libs/ui/animation: Allow iterating encoder frames multiple times

Git commit 34760a7870b00ba4baa9dd5c208ee473ad340229 by Carsten Hartenfels.
Committed on 27/07/2026 at 17:19.
Pushed by hartenfels into branch 'krita/6.0'.

Allow iterating encoder frames multiple times

GIF needs this because it must iterate the frames twice: once to create
a palette and then again to actually render the animated image. This
commit allows rewinding the iterator and specifying a ratio for the
progress slider so that it doesn't show 100% when the encoding is only
halfway done.

M  +14   -2    libs/ui/animation/KisMediaEncoderWrapper.cpp
M  +8    -1    libs/ui/animation/KisMediaEncoderWrapper.h

https://invent.kde.org/graphics/krita/-/commit/34760a7870b00ba4baa9dd5c208ee473ad340229

diff --git a/libs/ui/animation/KisMediaEncoderWrapper.cpp b/libs/ui/animation/KisMediaEncoderWrapper.cpp
index 67c8c95a613..2a2344dcd51 100644
--- a/libs/ui/animation/KisMediaEncoderWrapper.cpp
+++ b/libs/ui/animation/KisMediaEncoderWrapper.cpp
@@ -96,8 +96,12 @@ bool KisMediaEncoderRunnable::nextFrame(Frame &outFrame)
         }
 
         if (instances != 0) {
-            m_outputFrameNo += instances;
-            Q_EMIT sigProgressUpdated(m_outputFrameNo);
+            // GIF must spin through the input frames twice, once to generate a
+            // palette and then again to actually render the animated image. It
+            // sets the multiplier to 0.5 so that the progress bar shows values
+            // that make sense for the user, rather than reaching 100% halfway.
+            m_outputFrameNo += double(instances) * m_outputFrameNoMultiplier;
+            Q_EMIT sigProgressUpdated(int(m_outputFrameNo));
 
             // If we're on the last frame, we can append the linger time.
             if (fileIndex == lastIndex && m_needsLingerAfter) {
@@ -122,6 +126,14 @@ bool KisMediaEncoderRunnable::nextFrame(Frame &outFrame)
     return false;
 }
 
+void KisMediaEncoderRunnable::rewindFrames()
+{
+    m_inputTime = 0;
+    m_inputFileIndex = 0;
+    m_needsPreviewBefore = true;
+    m_needsLingerAfter = true;
+}
+
 KisMediaEncoderRunnable::EncodeResult KisMediaEncoderRunnable::prepareAndEncode(QString &outErrorMessage)
 {
     if (m_cancel) {
diff --git a/libs/ui/animation/KisMediaEncoderWrapper.h b/libs/ui/animation/KisMediaEncoderWrapper.h
index 2e0a7126fc4..062654d8bfb 100644
--- a/libs/ui/animation/KisMediaEncoderWrapper.h
+++ b/libs/ui/animation/KisMediaEncoderWrapper.h
@@ -111,7 +111,13 @@ protected:
         return m_cancel;
     }
 
+    void setOutputFrameNoMultiplier(double outputFrameNoMultiplier)
+    {
+        m_outputFrameNoMultiplier = outputFrameNoMultiplier;
+    }
+
     bool nextFrame(Frame &outFrame);
+    void rewindFrames();
 
 private:
     EncodeResult prepareAndEncode(QString &outErrorMessage);
@@ -119,7 +125,8 @@ private:
     KisMediaEncoderWrapperSettings m_settings;
     double m_inputTime = 0.0;
     int m_inputFileIndex = 0;
-    int m_outputFrameNo = 0;
+    double m_outputFrameNo = 0.0;
+    double m_outputFrameNoMultiplier = 1.0;
     bool m_needsPreviewBefore = true;
     bool m_needsLingerAfter = true;
     bool m_cancel = false;