noita-mapcap/bin/stitch/imagetile.go

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// Copyright (c) 2019-2022 David Vogel
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//
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT
package main
import (
"fmt"
"image"
_ "image/png"
"os"
"sync"
"time"
"github.com/nfnt/resize"
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)
type imageTile struct {
fileName string
scaleDivider int // Downscales the coordinates and images on the fly.
offset image.Point // Correction offset of the image, so that it aligns pixel perfect with other images. Determined by image matching.
image image.Image // Either a rectangle or an RGBA image. The bounds of this image are determined by the filename.
imageMutex *sync.RWMutex //
imageUsedFlag bool // Flag signalling, that the image was used recently
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pixelErrorSum uint64 // Sum of the difference between the (sub)pixels of all overlapping images. 0 Means that all overlapping images are identical.
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}
func (it *imageTile) GetImage() (*image.RGBA, error) {
it.imageMutex.RLock()
it.imageUsedFlag = true // Race condition may happen on this flag, but doesn't matter here.
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// Check if the image is already loaded
if img, ok := it.image.(*image.RGBA); ok {
it.imageMutex.RUnlock()
return img, nil
}
it.imageMutex.RUnlock()
// It's possible that the image got changed in between here
it.imageMutex.Lock()
defer it.imageMutex.Unlock()
// Check again if the image is already loaded
if img, ok := it.image.(*image.RGBA); ok {
return img, nil
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}
// Store rectangle of the old image
oldRect := it.image.Bounds()
file, err := os.Open(it.fileName)
if err != nil {
return &image.RGBA{}, err
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}
defer file.Close()
img, _, err := image.Decode(file)
if err != nil {
return &image.RGBA{}, err
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}
if it.scaleDivider > 1 {
img = resize.Resize(uint(oldRect.Dx()), uint(oldRect.Dy()), img, resize.NearestNeighbor)
}
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imgRGBA, ok := img.(*image.RGBA)
if !ok {
return &image.RGBA{}, fmt.Errorf("expected an RGBA image, got %T instead", img)
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}
// Restore the position of the image rectangle
imgRGBA.Rect = imgRGBA.Rect.Add(oldRect.Min)
it.image = imgRGBA
// Free the image after some time
go func() {
for it.imageUsedFlag {
time.Sleep(1 * time.Second)
it.imageUsedFlag = false
}
it.imageMutex.Lock()
defer it.imageMutex.Unlock()
it.image = it.image.Bounds()
}()
return imgRGBA, nil
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}
func (it *imageTile) OffsetBounds() image.Rectangle {
it.imageMutex.RLock()
defer it.imageMutex.RUnlock()
return it.image.Bounds().Add(it.offset)
}
func (it *imageTile) Bounds() image.Rectangle {
it.imageMutex.RLock()
defer it.imageMutex.RUnlock()
return it.image.Bounds()
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}
func (it *imageTile) String() string {
return fmt.Sprintf("<ImageTile \"%v\">", it.fileName)
}