Item Count GUI Rendering & Font Scaling

Overview

In vanilla Minecraft, item count numbers rendered on inventory slots are formatted for small numbers ($\le 64$). When stack numbers reach 4, 6, or 9 digits (e.g. 1000000), the rendered text overflows the 16x16 pixel slot bounds and overlaps neighboring inventory slots.

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🧮 Dynamic Font Scale-Down Algorithm

GuiGraphicsExtractorMixin intercepts client slot rendering and delegates to ItemCountRenderer.renderItemCount:

public class ItemCountRenderer {
    public static void renderItemCount(GuiGraphicsExtractor graphics, Font font, ItemStack itemStack, int x, int y, String countText) {
        if (itemStack.getCount() != 1 || countText != null) {
            String amount = countText == null ? String.valueOf(itemStack.getCount()) : countText;
            int textWidth = font.width(amount);
            
            float maxAllowedWidth = 16.0f;
            if (textWidth > maxAllowedWidth) {
                float scale = maxAllowedWidth / textWidth;
                
                Matrix3x2fStack pose = graphics.pose();
                pose.pushMatrix();
                
                float targetRight = x + 17;
                float targetBottom = y + 9;
                
                pose.translate(targetRight, targetBottom);
                pose.scale(scale, scale);
                
                graphics.text(font, amount, -textWidth, 0, -1, true);
                
                pose.popMatrix();
            } else {
                graphics.text(font, amount, x + 17 - textWidth, y + 9, -1, true);
            }
        }
    }
}

Scale Factor Formulation

Let $W_{\text{text}}$ be the font pixel width of the item count string, and $W_{\text{max}} = 16.0\text{px}$:

$$\text{Scale Factor } S = \begin{cases} 1.0 & \text{if } W_{\text{text}} \le 16.0 \ \frac{16.0}{W_{\text{text}}} & \text{if } W_{\text{text}} > 16.0 \end{cases}$$

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🖼️ Text Scale Comparison Table

Item Count	String Length	Standard Width ($W_{\text{text}}$)	Applied Scale ($S$)	Rendering Behavior
64	2 chars	$\sim 12\text{px}$	$1.00$	Standard Vanilla font size
1000	4 chars	$\sim 24\text{px}$	$0.66$	Dynamically scaled to fit slot
1000000	7 chars	$\sim 42\text{px}$	$0.38$	Compact high-precision fit