From de9be2025799c3676ecd346aadd7556cb889a1e8 Mon Sep 17 00:00:00 2001
From: Mike Walters <mike@flomp.net>
Date: Fri, 11 Sep 2015 20:10:16 +0100
Subject: [PATCH] Use QCache to cache FFT results

---
 spectrogram.cpp | 6 +++---
 spectrogram.h   | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/spectrogram.cpp b/spectrogram.cpp
index 0599186..189f97f 100644
--- a/spectrogram.cpp
+++ b/spectrogram.cpp
@@ -98,9 +98,9 @@ void Spectrogram::paintEvent(QPaintEvent *event)
 
 float* Spectrogram::getTile(off_t tile)
 {
-	auto iter = fftCache.find(qMakePair(fftSize, tile));
-	if (iter != fftCache.end())
-		return iter.value();
+	float *obj = fftCache.object(qMakePair(fftSize, tile));
+	if (obj != 0)
+		return obj;
 
 	float *dest = new float[tileSize];
 	float *ptr = dest;
diff --git a/spectrogram.h b/spectrogram.h
index 41c3902..cf748a2 100644
--- a/spectrogram.h
+++ b/spectrogram.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <QCache>
 #include <QWidget>
 #include "fft.h"
 #include "inputsource.h"
@@ -38,7 +39,7 @@ private:
 	FFT *fft = nullptr;
 	std::unique_ptr<float[]> window;
 	fftwf_complex *lineBuffer = nullptr;
-	QHash<QPair<int, off_t>, float*> fftCache;
+	QCache<QPair<int, off_t>, float> fftCache;
 	uint colormap[256];
 
 	int sampleRate;