Split image resizing and compression

CHANGELOG.md

@@ -17,10 +17,12 @@
 **Implemented enhancements:**
 
 - Added options to `PDFImage`, allowing more precise control about resizing and compression.
+- Improvements to internal image resizing and compression methods.
 
 **Closed issues:**
 
 - Issue #77
+- Issue #78
 
 ## [1.1.2](https://github.com/Techprimate/TPPDF/tree/1.1.2) (2018-07-12)
 [Full Changelog](https://github.com/Techprimate/TPPDF/compare/1.1.1...1.1.2)

Example/Tests/Graphics/PDFGraphics_Spec.swift

@@ -65,46 +65,79 @@ class PDFGraphics_Spec : QuickSpec {
                 expect(dashes).to(haveCount(0))
             }
 
-            it("can resize and compress an image") {
+            describe("resizing and compression") {
+
                 let base64String = "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"
 
                 let data: Data! = Data(base64Encoded: base64String)
                 expect(data).toNot(beNil())
 
-                let image: UIImage! = UIImage(data: data)
-                expect(image).toNot(beNil())
+                var image: UIImage!
+                let resultFrame = CGRect(x: 0, y: 0, width: 40, height: 40)
+
+                beforeEach {
+                    image = UIImage(data: data)
+                    expect(image).toNot(beNil())
+
+                    expect(image.size) == CGSize(width: 61, height: 68)
+                }
 
-                expect(image.size) == CGSize(width: 61, height: 68)
+                it("can resize image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
+                                                                    shouldResize: true,
+                                                                    shouldCompress: false,
+                                                                    quality: 0.2)
+                    expect(result) !== image
+                    expect(result.size) == CGSize(width: 25, height: 25)
+                }
+
+                it("can compress image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
+                                                                    shouldResize: false,
+                                                                    shouldCompress: true,
+                                                                    quality: 0.2)
+                    expect(result) !== image
+                    expect(result.size) == image.size
+                }
+
+                it("can resize and compress image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
+                                                                    shouldResize: true,
+                                                                    shouldCompress: true,
+                                                                    quality: 0.2)
+                    expect(result) !== image
+                    expect(result.size) == CGSize(width: 25.0, height: 25.0)
+                }
+
+                it("can return original image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
+                                                                    shouldResize: false,
+                                                                    shouldCompress: false,
+                                                                    quality: 0.2)
+                    expect(result) === image
+                }
+
+                it("can compress an image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
+                                                                    shouldResize: true,
+                                                                    shouldCompress: true,
+                                                                    quality: 0.0)
+                    expect(result) !== image
+                }
 
-                var compressFrame = CGRect(x: 0, y: 0, width: 40, height: 40)
-                var compressed = PDFGraphics.resizeAndCompressImage(image: image,
-                                                                    frame: compressFrame,
+                it("can resize and compress an image") {
+                    let result = PDFGraphics.resizeAndCompressImage(image: image,
+                                                                    frame: resultFrame,
                                                                     shouldResize: true,
                                                                     shouldCompress: true,
-                                                                    quality: 1.0)
-                expect(compressed.size) == compressFrame.size
-
-                compressFrame = CGRect(x: 0, y: 0, width: 40.0, height: 40.0)
-                compressed = PDFGraphics.resizeAndCompressImage(image: image,
-                                                                frame: compressFrame,
-                                                                shouldResize: true,
-                                                                shouldCompress: true,
-                                                                quality: 0.2)
-                expect(compressed.size) == CGSize(width: 25.0, height: 25.0)
-
-                compressed = PDFGraphics.resizeAndCompressImage(image: image,
-                                                                frame: compressFrame,
-                                                                shouldResize: true,
-                                                                shouldCompress: true,
-                                                                quality: 0.0)
-                expect(compressed.size) == CGSize(width: 8, height: 8)
-
-                compressed = PDFGraphics.resizeAndCompressImage(image: image,
-                                                                frame: compressFrame,
-                                                                shouldResize: false,
-                                                                shouldCompress: false,
-                                                                quality: 0.0)
-                expect(compressed) == image
+                                                                    quality: 0.0)
+                    expect(result.size) == CGSize(width: 8, height: 8)
+                }
             }
         }
     }

Source/Graphics/PDFGraphics.swift

@@ -159,28 +159,56 @@ class PDFGraphics {
         var finalImage = image
 
         if shouldResize {
-            // resize
-            var resizeFactor = (3 * quality > 1) ? 1 : 3 * quality
-            if resizeFactor == 0 {
-                resizeFactor = 0.2
-            }
-            let resizeImageSize = CGSize(width: frame.size.width * resizeFactor, height: frame.size.height * resizeFactor)
-
-            UIGraphicsBeginImageContext(resizeImageSize)
-            image.draw(in: CGRect(x: 0, y: 0, width: resizeImageSize.width, height: resizeImageSize.height))
-            finalImage = UIGraphicsGetImageFromCurrentImageContext() ?? finalImage
-            UIGraphicsEndImageContext()
+            finalImage = resize(image: finalImage, frame: frame, quality: quality)
         }
-
         if shouldCompress {
-            if let jpegData = UIImageJPEGRepresentation(finalImage, quality) {
-                finalImage = UIImage(data: jpegData) ?? finalImage
-            }
+            finalImage = compress(image: finalImage, quality: quality)
         }
 
         return finalImage
     }
 
+    /**
+     Draws a scaled version of the given `image` into the given `frame`.
+
+     - parameter image: Image to resize
+     - parameter frame: Frame in which the new image will fit
+     - parameter quality: Value between 0.0 and 1.0, where 1.0 is maximum quality, used for size calculations
+
+     - returns: Resized version of `image`
+     */
+    static func resize(image: UIImage, frame: CGRect, quality: CGFloat) -> UIImage {
+        let factor: CGFloat = min(3 * quality, 1)
+        let resizeFactor = factor.isZero ? 0.2 : factor
+
+        let size = CGSize(width: frame.width * resizeFactor,
+                          height: frame.height * resizeFactor)
+
+        UIGraphicsBeginImageContext(size)
+        image.draw(in: CGRect(origin: .zero, size: size))
+        let finalImage = UIGraphicsGetImageFromCurrentImageContext()
+        UIGraphicsEndImageContext()
+
+        return finalImage ?? image
+    }
+
+    /**
+     Performs JPEG compression on the given image.
+     If the given image can not be compressed, it will silently return the original image.
+
+     - parameter image: Image to compress
+     - parameter quality: Value between 0.0 and 1.0, where 1.0 is maximum quality/least compression
+     */
+    static func compress(image: UIImage, quality: CGFloat) -> UIImage {
+        guard let data = UIImageJPEGRepresentation(image, quality) else {
+            return image
+        }
+        guard let compressed = UIImage(data: data) else {
+            return image
+        }
+        return compressed
+    }
+
     /**
      Constants for filling, mostly used for debugging elements
      */

TPPDF.podspec

@@ -1,11 +1,11 @@
 Pod::Spec.new do |s|
   s.name             = 'TPPDF'
-  s.version          = '1.1.2'
+  s.version          = '1.2.0'
   s.summary          = 'TPPDF is a simple-to-use PDF builder for iOS'
   s.description      = <<-DESC
-    TPPDF is an object-based PDF builder.
+    TPPDF is an object-based PDF builder, completely built in Swift.
     You create a document by defining, adding and positioning different objects.
-    TPPDF then calculates the document and creates a PDF.
+    TPPDF then calculates the layout and renders a PDF file.
                        DESC
 
   s.homepage         = 'https://github.com/techprimate/TPPDF'