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mediaapi/thumbnailer: Make comparison code more readable

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This commit is contained in:
Robert Swain 2017-06-05 16:23:07 +02:00
parent a1e62a2b0b
commit 2825b4143b
1 changed files with 14 additions and 18 deletions
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32
src/github.com/matrix-org/dendrite/mediaapi/thumbnailer/thumbnailer.go
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@ -104,9 +104,7 @@ func SelectThumbnail(desired types.ThumbnailSize, thumbnails []*types.ThumbnailM
continue
}
metrics := calcThumbnailMetrics(thumbnail.ThumbnailSize, thumbnail.MediaMetadata, desired)
// Note: the result will be -1 for better than, 0 for the same as and 1 for worse than. Take better results only.
result := compareThumbnailMetrics(metrics, chosenMetrics, desired.ResizeMethod == "crop")
if result == -1 {
if isBetter := metrics.betterThan(chosenMetrics, desired.ResizeMethod == "crop"); isBetter {
chosenMetrics = metrics
chosenThumbnail = thumbnail
}
@ -117,9 +115,7 @@ func SelectThumbnail(desired types.ThumbnailSize, thumbnails []*types.ThumbnailM
continue
}
metrics := calcThumbnailMetrics(thumbnailSize, nil, desired)
// Note: the result will be -1 for better than, 0 for the same as and 1 for worse than. Take better results only.
result := compareThumbnailMetrics(metrics, chosenMetrics, desired.ResizeMethod == "crop")
if result == -1 {
if isBetter := metrics.betterThan(chosenMetrics, desired.ResizeMethod == "crop"); isBetter {
chosenMetrics = metrics
chosenThumbnailSize = &types.ThumbnailSize{
Width: thumbnailSize.Width,
@ -368,15 +364,15 @@ func boolToInt(b bool) int {
return 0
}
func compareThumbnailMetrics(a thumbnailMetrics, b thumbnailMetrics, desiredCrop bool) int {
func (a thumbnailMetrics) betterThan(b thumbnailMetrics, desiredCrop bool) bool {
// preference means returning -1
// prefer images that are not smaller
// e.g. isSmallerDiff > 0 means b is smaller than desired and a is not smaller
if a.isSmaller > b.isSmaller {
return 1
return false
} else if a.isSmaller < b.isSmaller {
return -1
return true
}
// prefer aspect ratios closer to desired only if desired cropped
@ -384,33 +380,33 @@ func compareThumbnailMetrics(a thumbnailMetrics, b thumbnailMetrics, desiredCrop
// desired scaled only accepts scaled images
if desiredCrop {
if a.aspect > b.aspect {
return 1
return false
} else if a.aspect < b.aspect {
return -1
return true
}
}
// prefer closer in size
if a.size > b.size {
return 1
return false
} else if a.size < b.size {
return -1
return true
}
// prefer images using the same method
// e.g. methodMismatchDiff > 0 means b's method is different from desired and a's matches the desired method
if a.methodMismatch > b.methodMismatch {
return 1
return false
} else if a.methodMismatch < b.methodMismatch {
return -1
return true
}
// prefer smaller files
if a.fileSize > b.fileSize {
return 1
return false
} else if a.fileSize < b.fileSize {
return -1
return true
}
return 0
return false
}