完成功能：改变图像显示的rgb波段；

1、可改变图像显示波段，当修改完成参数时实时刷新图像；
2、TOC中切换选中的多图层时，刷新渲染信息；
3、界面中保存图像的波长信息，参数修改时的选项就是准确的波长信息；

HPPA/imageControl.h

@@ -4,6 +4,7 @@
 #include <QNetworkRequest>
 #include <QNetworkReply>
 #include <QNetworkAccessManager>
+#include <vector>
 
 #include "ui_imgControl.h"
 
@@ -28,12 +29,26 @@ Q_SIGNALS:
 	void bandSelectionChanged(double rWave, double gWave, double bWave);
 
 private Q_SLOTS:
-	void onSpinRedChanged(double val);
-	void onSpinGreenChanged(double val);
-	void onSpinBlueChanged(double val);
-	void onSliderRedChanged(int val);
-	void onSliderGreenChanged(int val);
-	void onSliderBlueChanged(int val);
+	// Sync slider position while dragging spinbox (no render)
+	void onSpinRedValueChanged(double val);
+	void onSpinGreenValueChanged(double val);
+	void onSpinBlueValueChanged(double val);
+
+	// Sync spinbox display while dragging slider (no render)
+	void onSliderRedValueChanged(int val);
+	void onSliderGreenValueChanged(int val);
+	void onSliderBlueValueChanged(int val);
+
+	// Commit: spinbox Enter key pressed / focus lost
+	void onSpinRedEditingFinished();
+	void onSpinGreenEditingFinished();
+	void onSpinBlueEditingFinished();
+
+	// Commit: slider mouse released
+	void onSliderRedReleased();
+	void onSliderGreenReleased();
+	void onSliderBlueReleased();
+
 	void onTrueColorClicked();
 	void onColorInfraredClicked();
 
@@ -41,8 +56,14 @@ private:
 	void emitBandChange();
 	void blockAllSignals(bool block);
 
+	// Find the band index whose wavelength is closest to the given value
+	int nearestBandIndex(double wave) const;
+	// Set spinbox and slider to wavelength of the given band index
+	void setControlsToBandIndex(QDoubleSpinBox* spin, QSlider* slider, int idx);
+
 	Ui::ImageControl ui;
 	RasterLayer* m_activeLayer = nullptr;
 	double m_minWave = 374.5;
 	double m_maxWave = 948.1;
+	std::vector<double> m_wavelengths; // band wavelengths from header
 };