Add edit-undo history for tileset palette changes

forms/paletteeditor.ui

@@ -38,7 +38,11 @@
         </widget>
        </item>
        <item row="0" column="1">
-        <widget class="QSpinBox" name="spinBox_PaletteId"/>
+        <widget class="QSpinBox" name="spinBox_PaletteId">
+         <property name="focusPolicy">
+          <enum>Qt::NoFocus</enum>
+         </property>
+        </widget>
        </item>
       </layout>
      </widget>
@@ -1640,8 +1644,32 @@
      <height>21</height>
     </rect>
    </property>
+   <widget class="QMenu" name="menuEdit">
+    <property name="title">
+     <string>Edit</string>
+    </property>
+    <addaction name="actionUndo"/>
+    <addaction name="actionRedo"/>
+   </widget>
+   <addaction name="menuEdit"/>
   </widget>
   <widget class="QStatusBar" name="statusbar"/>
+  <action name="actionUndo">
+   <property name="text">
+    <string>Undo</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+Z</string>
+   </property>
+  </action>
+  <action name="actionRedo">
+   <property name="text">
+    <string>Redo</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+Y</string>
+   </property>
+  </action>
  </widget>
  <resources/>
  <connections/>

include/ui/paletteeditor.h

@@ -6,11 +6,20 @@
 #include <QFrame>
 #include <QLabel>
 #include "project.h"
+#include "history.h"
 
 namespace Ui {
 class PaletteEditor;
 }
 
+class PaletteHistoryItem {
+public:
+    QList<QRgb> colors;
+    PaletteHistoryItem(QList<QRgb> colors) {
+        this->colors = colors;
+    }
+};
+
 class PaletteEditor :  public QMainWindow {
     Q_OBJECT
 public:
@@ -26,6 +35,7 @@ private:
     QList<QLabel*> rgbLabels;
     Tileset *primaryTileset;
     Tileset *secondaryTileset;
+    QList<History<PaletteHistoryItem*>> palettesHistory;
     void disableSliderSignals();
     void enableSliderSignals();
     void initColorSliders();
@@ -33,6 +43,8 @@ private:
     void refreshColors();
     void refreshColor(int);
     void setColor(int);
+    void commitEditHistory();
+    void setColorsFromHistory(PaletteHistoryItem*, int);
 
 signals:
     void closed();
@@ -40,6 +52,8 @@ signals:
     void changedPalette(int);
 private slots:
     void on_spinBox_PaletteId_valueChanged(int arg1);
+    void on_actionUndo_triggered();
+    void on_actionRedo_triggered();
 };
 
 #endif // PALETTEEDITOR_H

src/ui/paletteeditor.cpp

@@ -100,6 +100,11 @@ PaletteEditor::PaletteEditor(Project *project, Tileset *primaryTileset, Tileset
     this->rgbLabels.append(this->ui->label_rgb14);
     this->rgbLabels.append(this->ui->label_rgb15);
 
+    // Setup edit-undo history for each of the palettes.
+    for (int i = 0; i < Project::getNumPalettesTotal(); i++) {
+        this->palettesHistory.append(History<PaletteHistoryItem*>());
+    }
+
     this->initColorSliders();
     this->refreshColorSliders();
     this->refreshColors();
@@ -188,6 +193,7 @@ void PaletteEditor::setColor(int colorIndex) {
             : this->secondaryTileset;
     (*tileset->palettes)[paletteNum][colorIndex] = qRgb(red, green, blue);
     this->refreshColor(colorIndex);
+    this->commitEditHistory();
     emit this->changedPaletteColor();
 }
 
@@ -196,3 +202,43 @@ void PaletteEditor::on_spinBox_PaletteId_valueChanged(int paletteId) {
     this->refreshColors();
     emit this->changedPalette(paletteId);
 }
+
+void PaletteEditor::commitEditHistory() {
+    int paletteId = this->ui->spinBox_PaletteId->value();
+    QList<QRgb> colors;
+    for (int i = 0; i < 16; i++) {
+        colors.append(qRgb(this->sliders[i][0]->value() * 8, this->sliders[i][1]->value() * 8, this->sliders[i][2]->value() * 8));
+    }
+    PaletteHistoryItem *commit = new PaletteHistoryItem(colors);
+    this->palettesHistory[paletteId].push(commit);
+}
+
+void PaletteEditor::on_actionUndo_triggered()
+{
+    int paletteId = this->ui->spinBox_PaletteId->value();
+    PaletteHistoryItem *prev = this->palettesHistory[paletteId].back();
+    this->setColorsFromHistory(prev, paletteId);
+}
+
+void PaletteEditor::on_actionRedo_triggered()
+{
+    int paletteId = this->ui->spinBox_PaletteId->value();
+    PaletteHistoryItem *next = this->palettesHistory[paletteId].next();
+    this->setColorsFromHistory(next, paletteId);
+}
+
+void PaletteEditor::setColorsFromHistory(PaletteHistoryItem *history, int paletteId) {
+    if (!history) return;
+
+    for (int i = 0; i < 16; i++) {
+        if (paletteId < Project::getNumPalettesPrimary()) {
+            (*this->primaryTileset->palettes)[paletteId][i] = history->colors.at(i);
+        } else {
+            (*this->secondaryTileset->palettes)[paletteId][i] = history->colors.at(i);
+        }
+    }
+
+    this->refreshColorSliders();
+    this->refreshColors();
+    emit this->changedPaletteColor();
+}