Description

SableRaf

opened on Aug 3, 2023

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Description

After the processing/processing4@c57069f update to use calculated text height instead of OS ascent for vertical centering, the textAscent() example seems to be broken in Processing 4.3. The function no longer aligns correctly with the top of the letter 'd' as described in the official documentation.

Expected Behavior

The horizontal line generated from the textAscent() example should align with the top of the letter 'd' as shown in the documentation: https://processing.org/reference/textAscent_.html.

Current Behavior

In Processing 4.3, the horizontal line is rendered below the top of the letter 'd'.
In Processing 4.2, the line was above the top of the letter 'd'.
Neither version aligns with the official documentation.

Steps to Reproduce

1. Run the provided textAscent() example code in both Processing 4.2 and 4.3.
2. Observe the misalignment of the horizontal line with the letter 'd'.
3. Compare the output with the expected outcome from the documentation.

Your Environment

• Processing version: 4.3
• Operating System and OS version: MacOS 13.4 (22F66)
• Other information: Apple Silicon (M1)

Screenshots

Expected outcome (from textAscent() documentation)

textAscent() example on Processing 4.2

textAscent() example on Processing 4.3

Activity

1. SableRaf commented on Aug 3, 2023

   

   SableRaf

   on Aug 3, 2023

   CollaboratorAuthor

   More actions

   Upon further investigation, it appears that the issue lies with the example provided rather than the textAscent() function itself. The use of the scalar in the example code seems to be causing the observed misalignment.

   The example can be simplified like so:

   size(400, 400);
   float base = height * 0.75;
   
   textSize(128);  // Set initial text size
   float a = textAscent();  // Calc ascent
   line(0, base-a, width, base-a);
   text("dp", 0, base);  // Draw text on baseline
   
   textSize(256);  // Increase text size
   a = textAscent();  // Recalc ascent
   line(160, base-a, width, base-a);
   text("dp", 160, base);  // Draw text on baseline

   Below is a more advanced example showing that textAscent() works correctly for all fonts, without scalar adjustment:

   PFont currentFont;
   String[] fontList;
   int fontIndex = 0;
   
   void setup() {
     size(400, 400);
   
     frameRate(2);
   
     fontList = PFont.list();
     printArray(fontList);
   }
   
   void draw() {
     background(150);  // Clear the screen every frame
   
     // Get the next font from the list
     String fontName = fontList[fontIndex];
     currentFont = createFont(fontName, 256);
     textFont(currentFont);
   
     float base = height * 0.75;
     
     translate(0,base);
   
     textSize(128);  // Set initial text size
     float a = textAscent();  // Calculate ascent
     line(0, -a, width, -a);
     text("dp", 0, 0);  // Draw text on baseline
   
     textSize(256);  // Increase text size
     a = textAscent();  // Recalculate ascent
     line(160, -a, width, -a);
     text("dp", 160, 0);  // Draw text on baseline
   
     // Move to the next font for the next frame
     fontIndex = (fontIndex + 1) % fontList.length;
   }
2. SableRaf

   transferred this issue frombenfry/processing4on Aug 3, 2023
3. SableRaf commented on Aug 3, 2023

   

   SableRaf

   on Aug 3, 2023

   CollaboratorAuthor

   More actions

   The following example shows that both textAscent() and textDescent() work without the need for scaling, on different fonts, and at various font sizes:

   PFont currentFont;
   String[] fontList;
   int fontIndex = 0;
   String[] words = {"apple", "banana", "cherry", "date", "elderberry", "fig", "grape"};  // Sample words, feel free to add more
   
   int baseFontSize = 128;
   
   int paddingLeft = 20;
   
   void setup() {
     size(800, 400);
   
     frameRate(1);
   
     fontList = PFont.list();
   }
   
   void draw() {
     background(230);  // Clear the screen every frame
   
     // Get the next font from the list
     String fontName = fontList[fontIndex];
     currentFont = createFont(fontName, 256);
     textFont(currentFont);
   
     float base = height * 0.5;
   
     float fontSize = baseFontSize - random(baseFontSize/2);
   
     fill(10);
     textSize(fontSize);
     
     float a = textAscent();  // Calculate ascent
     float d = textDescent();  // Calculate descent
     float h = a+d; // Calculate text height
     
     translate(0,base);
     
     stroke(#C93737);
     line(0,0,width,0); // Base line
     line(0, -a, width, -a);  // Ascent line
     line(0, d, width, d);  // Descent line
     
     String randomWord = words[int(random(words.length))];  // Randomly select a word
     text(randomWord, paddingLeft, 0);  // Draw text on baseline
   
     // Move to the next font for the next frame
     fontIndex = (fontIndex + 1) % fontList.length;
   }

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