default-resolution: Add clamping. Update documentation. Add test

Author: bamx23

TesseractOCR/G8Tesseract.h

@@ -92,7 +92,8 @@
 
 /**
  *  The resolution of the source image in pixels per inch so font size
- *  information can be calculated in results.
+ *  information can be calculated in results. It should be from 70 to
+ *  2400 or it will be clamped.
  *
  *  @default Default value is 72
  */

TesseractOCR/G8Tesseract.mm

@@ -22,7 +22,9 @@
 #import "genericvector.h"
 #import "strngs.h"
 
-static int const kG8DefaultResolution = 72;
+static NSInteger const kG8DefaultResolution = 72;
+static NSInteger const kG8MinCredibleResolution = 70;
+static NSInteger const kG8MaxCredibleResolution = 2400;
 
 namespace tesseract {
     class TessBaseAPI;
@@ -424,6 +426,15 @@ - (void)setRect:(CGRect)rect
 - (void)setSourceResolution:(NSInteger)sourceResolution
 {
     if (_sourceResolution != sourceResolution) {
+        if (sourceResolution > kG8MaxCredibleResolution) {
+            NSLog(@"Source resolution is too big: %ld > %ld", (long)sourceResolution, (long)kG8MaxCredibleResolution);
+            sourceResolution = kG8MaxCredibleResolution;
+        }
+        else if (sourceResolution < kG8MinCredibleResolution) {
+            NSLog(@"Source resolution is too small: %ld < %ld", (long)sourceResolution, (long)kG8MinCredibleResolution);
+            sourceResolution = kG8MinCredibleResolution;
+        }
+        
         _sourceResolution = sourceResolution;
 
         _tesseract->SetSourceResolution((int)sourceResolution);

TestsProject/TestsProjectTests/G8RecognitionTestsHelper.h

@@ -31,6 +31,7 @@ typedef NS_ENUM(NSUInteger, G8CustomPreprocessing) {
 @property (nonatomic, assign) CGSize boundingSizeForResizing;
 @property (nonatomic, assign) G8CustomPreprocessing customPreprocessingType;
 
+- (void)setupTesseract;
 - (void)recognizeImage;
 - (void)recognizeImageUsingOperation;
 - (UIImage *)thresholdedImageForImage:(UIImage *)sourceImage;

TestsProject/TestsProjectTests/G8RecognitionTestsHelper.m

@@ -50,6 +50,10 @@ - (void)waitTimeLmit:(NSTimeInterval)maximumWait whileTrue:(BOOL (^)())shouldKee
 
 - (void)setupTesseract
 {
+    if (self.tesseract == nil) {
+        self.tesseract = [[G8Tesseract alloc] init];
+    }
+    
     self.tesseract.delegate = self;
 
     self.tesseract.language = kG8Languages;

TestsProject/TestsProjectTests/RecognitionTests.m

@@ -125,6 +125,16 @@
         [[theValue(block.level) should] equal:theValue(G8PageIteratorLevelWord)];
     });
 
+    it(@"Should clamp source resolution", ^{
+        [helper setupTesseract];
+
+        helper.tesseract.sourceResolution = 50;
+        [[theValue(helper.tesseract.sourceResolution) should] beInTheIntervalFrom:theValue(70) to:theValue(2400)];
+
+        helper.tesseract.sourceResolution = 3000;
+        [[theValue(helper.tesseract.sourceResolution) should] beInTheIntervalFrom:theValue(70) to:theValue(2400)];
+    });
+
     it(@"Should draw blocks on image", ^{
         [helper recognizeImage];